diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index 1e1d8a0..bbe24c0 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -9,10 +9,11 @@ jobs:
     steps:
       - name: Check out code
         uses: actions/checkout@v2
-      - name: Set up JDK 1.8
-        uses: actions/setup-java@v1
+      - name: Set up JDK 11
+        uses: actions/setup-java@v2
         with:
-          java-version: 1.8
+          distribution: adopt
+          java-version: 11
       - name: Debug build
         run: ./gradlew assembleDebug --stacktrace
       - name: Unit test
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 2097f0f..7bfc28a 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -1,9 +1,8 @@
 name: Publish
 
 on:
-  push:
-    tags:
-      - "*-RELEASE"
+  release:
+    types: [ released ]
 
 jobs:
   publish:
@@ -12,10 +11,11 @@ jobs:
     steps:
       - name: Check out code
         uses: actions/checkout@v2
-      - name: Set up JDK 1.8
-        uses: actions/setup-java@v1
+      - name: Set up JDK 11
+        uses: actions/setup-java@v2
         with:
-          java-version: 1.8
+          distribution: adopt
+          java-version: 11
       - name: Release build and source jar generation
         run: ./gradlew assembleRelease androidSourcesJar -x :app:assembleRelease
       - name: Publish to MavenCentral
diff --git a/README.md b/README.md
index 6318ef6..530f808 100644
--- a/README.md
+++ b/README.md
@@ -27,7 +27,7 @@ Log.d("LOGIN_COUNT", "Count: ${settings.loginCount}")
 You can include _Krate_ in your project from the `mavenCentral()` repository, like so:
 
 ```groovy
-implementation 'hu.autsoft:krate:1.1.0'
+implementation 'hu.autsoft:krate:1.2.0'
 ```
 
 # Optionals vs defaults
@@ -152,7 +152,7 @@ class CustomMoshiKrate(context: Context) : SimpleKrate(context) {
 If you only want to use Moshi adapters that you generate via Moshi's [codegen facilities](https://github.com/square/moshi#codegen), you can use the following Krate artifact in your project to make use of these adapters: 
 
 ```groovy
-implementation 'hu.autsoft:krate-moshi-codegen:1.1.0'
+implementation 'hu.autsoft:krate-moshi-codegen:1.2.0'
 ```
 
 This will give you a default `Moshi` instance created by a call to `Moshi.Builder().build()`. This instance will find and use any of the adapters generated by Moshi's codegen automatically.
@@ -162,7 +162,7 @@ This will give you a default `Moshi` instance created by a call to `Moshi.Builde
 If you rely on [reflection](https://github.com/square/moshi#reflection) for your Moshi serialization, and therefore need a `KotlinJsonAdapterFactory` included in your `Moshi` instance, use the following Krate Moshi dependency:
 
 ```groovy
-implementation 'hu.autsoft:krate-moshi-reflect:1.1.0'
+implementation 'hu.autsoft:krate-moshi-reflect:1.2.0'
 ```
 
 The default `Moshi` instance from this dependency will include the aforementioned factory, and be able to serialize any Kotlin class. Note that this approach relies on the `kotlin-reflect` library, which is a large dependency.
@@ -174,7 +174,7 @@ You may choose to use Moshi's codegen for some classes in your project, and seri
 The `krate-kotlinx` artifact provides a `kotlinxPref` delegate which can store any arbitrary type, as long as Kotlinx.serializazion can serialize and deserialize it. This addon, like the base library, is available from `mavenCentral()`:
 
 ```groovy
-implementation 'hu.autsoft:krate-kotlinx:1.1.0'
+implementation 'hu.autsoft:krate-kotlinx:1.2.0'
 ```
 
 Its usage is the same as with any of the base library's delegates:
@@ -206,7 +206,7 @@ class CustomKotlinxKrate(context: Context) : SimpleKrate(context) {
 The `krate-gson` artifact provides a `gsonPref` delegate which can store any arbitrary type, as long as Gson can serialize and deserialize it. This addon, like the base library, is available from `mavenCentral()`:
 
 ```groovy
-implementation 'hu.autsoft:krate-gson:1.1.0'
+implementation 'hu.autsoft:krate-gson:1.2.0'
 ```
 
 Its basic usage is the same as with any of the base library's delegates:
diff --git a/app/build.gradle b/app/build.gradle
index cad617e..3d85abb 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -1,6 +1,5 @@
 apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
-apply plugin: 'kotlin-android-extensions'
 
 android {
     compileSdkVersion compile_sdk
@@ -17,16 +16,18 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }
+    buildFeatures {
+        viewBinding true
+    }
 }
 
 dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
-    implementation 'com.google.android.material:material:1.2.1'
-    implementation 'androidx.appcompat:appcompat:1.2.0'
-    implementation 'androidx.constraintlayout:constraintlayout:2.0.2'
+    implementation 'com.google.android.material:material:1.4.0'
+    implementation 'androidx.appcompat:appcompat:1.3.1'
+    implementation 'androidx.constraintlayout:constraintlayout:2.1.0'
 
     // Third-party SharedPreferences implementations
-    implementation "androidx.security:security-crypto:1.1.0-alpha02"
+    implementation "androidx.security:security-crypto:1.1.0-alpha03"
     implementation 'com.frybits.harmony:harmony:1.1.2'
 
     implementation project(path: ':krate')
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 6a4a625..d36d87a 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -3,13 +3,15 @@
     package="hu.autsoft.krateexample">
 
     <application
-        android:allowBackup="true"
+        android:allowBackup="false"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
-        <activity android:name=".MainActivity">
+        <activity
+            android:name=".MainActivity"
+            android:exported="true">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 
diff --git a/app/src/main/java/hu/autsoft/krateexample/ExampleActivity.kt b/app/src/main/java/hu/autsoft/krateexample/ExampleActivity.kt
index ca9bd79..7af8757 100644
--- a/app/src/main/java/hu/autsoft/krateexample/ExampleActivity.kt
+++ b/app/src/main/java/hu/autsoft/krateexample/ExampleActivity.kt
@@ -2,10 +2,10 @@ package hu.autsoft.krateexample
 
 import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
+import hu.autsoft.krateexample.databinding.ActivityExampleBinding
 import hu.autsoft.krateexample.krates.ExampleCustomKrate
 import hu.autsoft.krateexample.krates.ExampleSettings
 import hu.autsoft.krateexample.krates.ExampleSimpleKrate
-import kotlinx.android.synthetic.main.activity_example.*
 
 class ExampleActivity : AppCompatActivity() {
 
@@ -17,9 +17,13 @@ class ExampleActivity : AppCompatActivity() {
 
     lateinit var exampleSettings: ExampleSettings
 
+    private lateinit var binding: ActivityExampleBinding
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_example)
+
+        binding = ActivityExampleBinding.inflate(layoutInflater)
+        setContentView(binding.root)
 
         when (intent.getStringExtra(KEY_KRATE_TYPE)) {
             TYPE_SIMPLE -> {
@@ -37,23 +41,24 @@ class ExampleActivity : AppCompatActivity() {
     override fun onResume() {
         super.onResume()
 
-        booleanPreference.isChecked = exampleSettings.exampleBoolean
-        floatPreferenceInput.setText(exampleSettings.exampleFloat.toString())
-        intPreferenceInput.setText(exampleSettings.exampleInt.toString())
-        longPreferenceInput.setText(exampleSettings.exampleLong.toString())
-        stringPreferenceInput.setText(exampleSettings.exampleString)
-        stringSetPreferenceInput.setText(exampleSettings.exampleStringSet.joinToString(separator = ", "))
+        binding.booleanPreference.isChecked = exampleSettings.exampleBoolean
+        binding.floatPreferenceInput.setText(exampleSettings.exampleFloat.toString())
+        binding.intPreferenceInput.setText(exampleSettings.exampleInt.toString())
+        binding.longPreferenceInput.setText(exampleSettings.exampleLong.toString())
+        binding.stringPreferenceInput.setText(exampleSettings.exampleString)
+        binding.stringSetPreferenceInput.setText(exampleSettings.exampleStringSet.joinToString(separator = ", "))
     }
 
     override fun onPause() {
         super.onPause()
 
-        exampleSettings.exampleBoolean = booleanPreference.isChecked
-        exampleSettings.exampleFloat = floatPreferenceInput.text.toString().toFloat()
-        exampleSettings.exampleInt = intPreferenceInput.text.toString().toInt()
-        exampleSettings.exampleLong = longPreferenceInput.text.toString().toLong()
-        exampleSettings.exampleString = stringPreferenceInput.text.toString()
-        exampleSettings.exampleStringSet = stringSetPreferenceInput.text.toString().split(",").map(String::trim).toSet()
+        exampleSettings.exampleBoolean = binding.booleanPreference.isChecked
+        exampleSettings.exampleFloat = binding.floatPreferenceInput.text.toString().toFloat()
+        exampleSettings.exampleInt = binding.intPreferenceInput.text.toString().toInt()
+        exampleSettings.exampleLong = binding.longPreferenceInput.text.toString().toLong()
+        exampleSettings.exampleString = binding.stringPreferenceInput.text.toString()
+        exampleSettings.exampleStringSet =
+            binding.stringSetPreferenceInput.text.toString().split(",").map(String::trim).toSet()
     }
 
 }
diff --git a/app/src/main/java/hu/autsoft/krateexample/MainActivity.kt b/app/src/main/java/hu/autsoft/krateexample/MainActivity.kt
index 2cbb509..d34453e 100644
--- a/app/src/main/java/hu/autsoft/krateexample/MainActivity.kt
+++ b/app/src/main/java/hu/autsoft/krateexample/MainActivity.kt
@@ -3,22 +3,26 @@ package hu.autsoft.krateexample
 import android.content.Intent
 import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
-import kotlinx.android.synthetic.main.activity_main.*
+import hu.autsoft.krateexample.databinding.ActivityMainBinding
 
 class MainActivity : AppCompatActivity() {
 
+    private lateinit var binding: ActivityMainBinding
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_main)
 
-        btnSimpleKrate.setOnClickListener {
+        binding = ActivityMainBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        binding.btnSimpleKrate.setOnClickListener {
             val intent = Intent(this, ExampleActivity::class.java)
-                    .putExtra(ExampleActivity.KEY_KRATE_TYPE, ExampleActivity.TYPE_SIMPLE)
+                .putExtra(ExampleActivity.KEY_KRATE_TYPE, ExampleActivity.TYPE_SIMPLE)
             startActivity(intent)
         }
-        btnCustomKrate.setOnClickListener {
+        binding.btnCustomKrate.setOnClickListener {
             val intent = Intent(this, ExampleActivity::class.java)
-                    .putExtra(ExampleActivity.KEY_KRATE_TYPE, ExampleActivity.TYPE_CUSTOM)
+                .putExtra(ExampleActivity.KEY_KRATE_TYPE, ExampleActivity.TYPE_CUSTOM)
             startActivity(intent)
         }
     }
diff --git a/app/src/main/java/hu/autsoft/krateexample/krates/ExampleThirdPartyKrates.kt b/app/src/main/java/hu/autsoft/krateexample/krates/ExampleThirdPartyKrates.kt
index 80b0a23..fcca564 100644
--- a/app/src/main/java/hu/autsoft/krateexample/krates/ExampleThirdPartyKrates.kt
+++ b/app/src/main/java/hu/autsoft/krateexample/krates/ExampleThirdPartyKrates.kt
@@ -19,16 +19,16 @@ class EncryptedKrate(applicationContext: Context) : Krate {
         // https://developer.android.com/topic/security/data
         // https://developer.android.com/reference/kotlin/androidx/security/crypto/EncryptedSharedPreferences
         val masterKeyAlias = MasterKey.Builder(applicationContext)
-                .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
-                .build()
+            .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
+            .build()
         val sharedPrefsFile = "my_sensitive_data.txt"
 
         sharedPreferences = EncryptedSharedPreferences.create(
-                applicationContext,
-                sharedPrefsFile,
-                masterKeyAlias,
-                EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
-                EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+            applicationContext,
+            sharedPrefsFile,
+            masterKeyAlias,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
         )
     }
 
diff --git a/build.gradle b/build.gradle
index af90496..b8dcff9 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,14 +1,14 @@
 buildscript {
-    ext.kotlin_version = '1.5.20'
-    ext.krate_version = '1.1.0'
+    ext.kotlin_version = '1.5.31'
+    ext.krate_version = '1.2.0'
 
     ext.moshi_version = '1.12.0'
     ext.junit_version = '4.13.2'
-    ext.robolectric_version = '4.5.1'
+    ext.robolectric_version = '4.6.1'
 
     ext.min_sdk = 15
-    ext.compile_sdk = 29
-    ext.target_sdk = 29
+    ext.compile_sdk = 31
+    ext.target_sdk = 31
 
     repositories {
         google()
@@ -17,7 +17,7 @@ buildscript {
         maven { url "https://plugins.gradle.org/m2/" }
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.2.2'
+        classpath 'com.android.tools.build:gradle:7.0.2'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
         classpath "org.jetbrains.kotlin:kotlin-serialization:$kotlin_version"
         classpath "io.github.gradle-nexus:publish-plugin:1.1.0"
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index e708b1c..7454180 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradlew b/gradlew
index 4f906e0..744e882 100755
--- a/gradlew
+++ b/gradlew
@@ -72,7 +72,7 @@ case "`uname`" in
   Darwin* )
     darwin=true
     ;;
-  MINGW* )
+  MSYS* | MINGW* )
     msys=true
     ;;
   NONSTOP* )
diff --git a/krate-gson/build.gradle b/krate-gson/build.gradle
index e4db252..2c5f7c7 100644
--- a/krate-gson/build.gradle
+++ b/krate-gson/build.gradle
@@ -11,10 +11,6 @@ android {
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
-    sourceSets {
-        main.java.srcDirs += 'src/main/kotlin'
-    }
-
     buildFeatures {
         buildConfig false
     }
@@ -32,8 +28,7 @@ tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
 
 dependencies {
     implementation project(':krate')
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
-    api 'com.google.code.gson:gson:2.8.7'
+    api 'com.google.code.gson:gson:2.8.8'
 
     testImplementation "junit:junit:$junit_version"
     testImplementation "org.robolectric:robolectric:$robolectric_version"
diff --git a/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/Functions.kt b/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/Functions.kt
index ddfad47..6719f75 100644
--- a/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/Functions.kt
+++ b/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/Functions.kt
@@ -4,33 +4,46 @@ package hu.autsoft.krate.gson
 
 import com.google.gson.reflect.TypeToken
 import hu.autsoft.krate.Krate
-import hu.autsoft.krate.gson.default.GsonDelegateWithDefault
-import hu.autsoft.krate.gson.optional.GsonDelegate
+import hu.autsoft.krate.gson.default.GsonDelegateWithDefaultFactory
+import hu.autsoft.krate.gson.optional.GsonDelegateFactory
 import java.lang.reflect.Type
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 
 /**
  * Creates an optional preference of type T with the given [key] in this [Krate] instance.
  * This instance will be serialized using Gson.
  */
-public inline fun <reified T : Any> Krate.gsonPref(key: String): ReadWriteProperty<Krate, T?> {
+public inline fun <reified T : Any> Krate.gsonPref(
+    key: String,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
     return gsonPrefImpl(key, object : TypeToken<T>() {}.type)
 }
 
 @PublishedApi
-internal fun <T : Any> Krate.gsonPrefImpl(key: String, type: Type): ReadWriteProperty<Krate, T?> {
-    return GsonDelegate(key, type)
+internal fun <T : Any> Krate.gsonPrefImpl(
+    key: String,
+    type: Type,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
+    return GsonDelegateFactory(key, type)
 }
 
 /**
  * Creates a non-optional preference of type T with the given [key] and [defaultValue] in this [Krate] instance.
  * This instance will be serialized using Gson.
  */
-public inline fun <reified T : Any> Krate.gsonPref(key: String, defaultValue: T): ReadWriteProperty<Krate, T> {
+public inline fun <reified T : Any> Krate.gsonPref(
+    key: String,
+    defaultValue: T,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
     return gsonPrefImpl(key, defaultValue, object : TypeToken<T>() {}.type)
 }
 
 @PublishedApi
-internal fun <T : Any> Krate.gsonPrefImpl(key: String, defaultValue: T, type: Type): ReadWriteProperty<Krate, T> {
-    return GsonDelegateWithDefault(key, defaultValue, type)
+internal fun <T : Any> Krate.gsonPrefImpl(
+    key: String,
+    defaultValue: T,
+    type: Type,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
+    return GsonDelegateWithDefaultFactory(key, defaultValue, type)
 }
diff --git a/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/ValidatedFunctions.kt b/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/ValidatedFunctions.kt
index 2366d9e..4dd05b3 100644
--- a/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/ValidatedFunctions.kt
+++ b/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/ValidatedFunctions.kt
@@ -4,11 +4,12 @@ package hu.autsoft.krate.gson
 
 import com.google.gson.reflect.TypeToken
 import hu.autsoft.krate.Krate
-import hu.autsoft.krate.gson.default.GsonDelegateWithDefault
-import hu.autsoft.krate.gson.optional.GsonDelegate
+import hu.autsoft.krate.gson.default.GsonDelegateWithDefaultFactory
+import hu.autsoft.krate.gson.optional.GsonDelegateFactory
 import hu.autsoft.krate.internal.InternalKrateApi
-import hu.autsoft.krate.validation.ValidatedPreferenceDelegate
+import hu.autsoft.krate.validation.ValidatedPreferenceDelegateFactory
 import java.lang.reflect.Type
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 
 /**
@@ -16,27 +17,27 @@ import kotlin.properties.ReadWriteProperty
  * This value will be serialized using Gson.
  */
 @Deprecated(
-        message = "Use .validate {} on a gsonPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.gsonPref<T>(key).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a gsonPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.gsonPref<T>(key).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public inline fun <reified T : Any> Krate.gsonPref(
-        key: String,
-        noinline isValid: (newValue: T?) -> Boolean,
-): ReadWriteProperty<Krate, T?> {
+    key: String,
+    noinline isValid: (newValue: T?) -> Boolean,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
     return gsonPrefImpl(key, object : TypeToken<T>() {}.type, isValid)
 }
 
 @PublishedApi
 internal fun <T : Any> Krate.gsonPrefImpl(
-        key: String,
-        type: Type,
-        isValid: (newValue: T?) -> Boolean,
-): ReadWriteProperty<Krate, T?> {
-    return ValidatedPreferenceDelegate(GsonDelegate(key, type), isValid)
+    key: String,
+    type: Type,
+    isValid: (newValue: T?) -> Boolean,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
+    return ValidatedPreferenceDelegateFactory(GsonDelegateFactory(key, type), isValid)
 }
 
 /**
@@ -45,27 +46,27 @@ internal fun <T : Any> Krate.gsonPrefImpl(
  * This value will be serialized using Gson.
  */
 @Deprecated(
-        message = "Use .validate {} on a gsonPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.gsonPref(key, defaultValue).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a gsonPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.gsonPref(key, defaultValue).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public inline fun <reified T : Any> Krate.gsonPref(
-        key: String,
-        defaultValue: T,
-        noinline isValid: (newValue: T) -> Boolean,
-): ReadWriteProperty<Krate, T> {
+    key: String,
+    defaultValue: T,
+    noinline isValid: (newValue: T) -> Boolean,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
     return gsonPrefImpl(key, defaultValue, object : TypeToken<T>() {}.type, isValid)
 }
 
 @PublishedApi
 internal fun <T : Any> Krate.gsonPrefImpl(
-        key: String,
-        defaultValue: T,
-        type: Type,
-        isValid: (newValue: T) -> Boolean,
-): ReadWriteProperty<Krate, T> {
-    return ValidatedPreferenceDelegate(GsonDelegateWithDefault(key, defaultValue, type), isValid)
+    key: String,
+    defaultValue: T,
+    type: Type,
+    isValid: (newValue: T) -> Boolean,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
+    return ValidatedPreferenceDelegateFactory(GsonDelegateWithDefaultFactory(key, defaultValue, type), isValid)
 }
diff --git a/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/default/GsonDelegateWithDefault.kt b/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/default/GsonDelegateWithDefault.kt
index b776597..febc78d 100644
--- a/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/default/GsonDelegateWithDefault.kt
+++ b/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/default/GsonDelegateWithDefault.kt
@@ -1,32 +1,44 @@
 package hu.autsoft.krate.gson.default
 
+import com.google.gson.TypeAdapter
+import com.google.gson.reflect.TypeToken
 import hu.autsoft.krate.Krate
 import hu.autsoft.krate.gson.internalGson
 import hu.autsoft.krate.gson.util.edit
 import java.lang.reflect.Type
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
-
-internal class GsonDelegateWithDefault<T : Any>(
-        private val key: String,
-        private val default: T,
-        private val type: Type,
+private class GsonDelegateWithDefault<T : Any>(
+    private val key: String,
+    private val default: T,
+    private val adapter: TypeAdapter<T>,
 ) : ReadWriteProperty<Krate, T> {
-
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): T {
         if (!thisRef.sharedPreferences.contains(key)) {
             return default
         }
 
         val string = thisRef.sharedPreferences.getString(key, null)
-        return thisRef.internalGson.fromJson(string, type)
+        return adapter.fromJson(string)
     }
 
     override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T) {
         thisRef.sharedPreferences.edit {
-            putString(key, thisRef.internalGson.toJson(value))
+            putString(key, adapter.toJson(value))
         }
     }
+}
 
+internal class GsonDelegateWithDefaultFactory<T : Any>(
+    private val key: String,
+    private val default: T,
+    private val type: Type,
+) : PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
+    override fun provideDelegate(thisRef: Krate, property: KProperty<*>): ReadWriteProperty<Krate, T> {
+        @Suppress("UNCHECKED_CAST")
+        val adapter: TypeAdapter<T> = thisRef.internalGson.getAdapter(TypeToken.get(type)) as TypeAdapter<T>
+        return GsonDelegateWithDefault(key, default, adapter)
+    }
 }
diff --git a/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/optional/GsonDelegate.kt b/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/optional/GsonDelegate.kt
index f912abc..01dde64 100644
--- a/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/optional/GsonDelegate.kt
+++ b/krate-gson/src/main/kotlin/hu/autsoft/krate/gson/optional/GsonDelegate.kt
@@ -1,24 +1,25 @@
 package hu.autsoft.krate.gson.optional
 
+import com.google.gson.TypeAdapter
+import com.google.gson.reflect.TypeToken
 import hu.autsoft.krate.Krate
 import hu.autsoft.krate.gson.internalGson
 import hu.autsoft.krate.gson.util.edit
 import java.lang.reflect.Type
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
-
-internal class GsonDelegate<T : Any>(
-        private val key: String,
-        private val type: Type,
+private class GsonDelegate<T : Any>(
+    private val key: String,
+    private val adapter: TypeAdapter<T>,
 ) : ReadWriteProperty<Krate, T?> {
-
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
         return if (!thisRef.sharedPreferences.contains(key)) {
             null
         } else {
             val string = thisRef.sharedPreferences.getString(key, null)
-            thisRef.internalGson.fromJson(string, type)
+            adapter.fromJson(string)
         }
     }
 
@@ -29,9 +30,19 @@ internal class GsonDelegate<T : Any>(
             }
         } else {
             thisRef.sharedPreferences.edit {
-                putString(key, thisRef.internalGson.toJson(value))
+                putString(key, adapter.toJson(value))
             }
         }
     }
+}
 
+internal class GsonDelegateFactory<T : Any>(
+    private val key: String,
+    private val type: Type,
+) : PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
+    override fun provideDelegate(thisRef: Krate, property: KProperty<*>): ReadWriteProperty<Krate, T?> {
+        @Suppress("UNCHECKED_CAST")
+        val adapter: TypeAdapter<T> = thisRef.internalGson.getAdapter(TypeToken.get(type)) as TypeAdapter<T>
+        return GsonDelegate(key, adapter)
+    }
 }
diff --git a/krate-gson/src/test/java/hu/autsoft/krate/gson/GsonTestKrate.kt b/krate-gson/src/test/java/hu/autsoft/krate/gson/GsonTestKrate.kt
index 985229a..ee46f64 100644
--- a/krate-gson/src/test/java/hu/autsoft/krate/gson/GsonTestKrate.kt
+++ b/krate-gson/src/test/java/hu/autsoft/krate/gson/GsonTestKrate.kt
@@ -28,14 +28,14 @@ internal class GsonTestKrate(context: Context) : SimpleKrate(context) {
 
     var validatedValue: TestModel
             by gsonPref(key = "validatedValue", defaultValue = DEFAULT_SIMPLE_VALUE)
-                    .validate { newValue ->
-                        newValue.x < newValue.y // arbitrary rule
-                    }
+                .validate { newValue ->
+                    newValue.x < newValue.y // arbitrary rule
+                }
 
     var validatedOptionalValue: List<TestModel>?
             by gsonPref<List<TestModel>>(key = "validatedOptionalValue")
-                    .validate { newValue ->
-                        newValue.isNullOrEmpty().not()
-                    }
+                .validate { newValue ->
+                    newValue.isNullOrEmpty().not()
+                }
 
 }
diff --git a/krate-gson/src/test/java/hu/autsoft/krate/gson/test/GsonDelegateTest.kt b/krate-gson/src/test/java/hu/autsoft/krate/gson/test/GsonDelegateTest.kt
index f6bbaf4..e0122da 100644
--- a/krate-gson/src/test/java/hu/autsoft/krate/gson/test/GsonDelegateTest.kt
+++ b/krate-gson/src/test/java/hu/autsoft/krate/gson/test/GsonDelegateTest.kt
@@ -47,9 +47,9 @@ internal class GsonDelegateTest {
     @Test
     fun testSetListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValues = list
@@ -60,9 +60,9 @@ internal class GsonDelegateTest {
     @Test
     fun testRemoveListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValues = list
diff --git a/krate-gson/src/test/java/hu/autsoft/krate/gson/test/GsonDelegateWithDefaultTest.kt b/krate-gson/src/test/java/hu/autsoft/krate/gson/test/GsonDelegateWithDefaultTest.kt
index bf302c6..1be43fe 100644
--- a/krate-gson/src/test/java/hu/autsoft/krate/gson/test/GsonDelegateWithDefaultTest.kt
+++ b/krate-gson/src/test/java/hu/autsoft/krate/gson/test/GsonDelegateWithDefaultTest.kt
@@ -37,9 +37,9 @@ internal class GsonDelegateWithDefaultTest {
     @Test
     fun testListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValuesWithDefault = list
diff --git a/krate-gson/src/test/java/hu/autsoft/krate/gson/test/ValidatedGsonDelegateTest.kt b/krate-gson/src/test/java/hu/autsoft/krate/gson/test/ValidatedGsonDelegateTest.kt
index bc4014c..65d1712 100644
--- a/krate-gson/src/test/java/hu/autsoft/krate/gson/test/ValidatedGsonDelegateTest.kt
+++ b/krate-gson/src/test/java/hu/autsoft/krate/gson/test/ValidatedGsonDelegateTest.kt
@@ -36,8 +36,8 @@ internal class ValidatedGsonDelegateTest {
     @Test
     fun testValidOptionalValue() {
         val newValue = listOf(
-                TestModel(20, 21.0, ""),
-                TestModel(10, 5.0, "")
+            TestModel(20, 21.0, ""),
+            TestModel(10, 5.0, "")
         )
 
         krate.validatedOptionalValue = newValue
diff --git a/krate-kotlinx/build.gradle b/krate-kotlinx/build.gradle
index 7f5ff1c..51b2146 100644
--- a/krate-kotlinx/build.gradle
+++ b/krate-kotlinx/build.gradle
@@ -12,10 +12,6 @@ android {
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
-    sourceSets {
-        main.java.srcDirs += 'src/main/kotlin'
-    }
-
     buildFeatures {
         buildConfig false
     }
@@ -33,9 +29,8 @@ tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
 
 dependencies {
     implementation project(':krate')
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
 
-    implementation "org.jetbrains.kotlinx:kotlinx-serialization-json:1.2.1"
+    implementation "org.jetbrains.kotlinx:kotlinx-serialization-json:1.2.2"
 
     testImplementation "junit:junit:$junit_version"
     testImplementation "org.robolectric:robolectric:$robolectric_version"
diff --git a/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/Functions.kt b/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/Functions.kt
index 7bfc65c..c128239 100644
--- a/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/Functions.kt
+++ b/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/Functions.kt
@@ -3,8 +3,9 @@
 package hu.autsoft.krate.kotlinx
 
 import hu.autsoft.krate.Krate
-import hu.autsoft.krate.kotlinx.default.KotlinxDelegateWithDefault
-import hu.autsoft.krate.kotlinx.optional.KotlinxDelegate
+import hu.autsoft.krate.kotlinx.default.KotlinxDelegateWithDefaultFactory
+import hu.autsoft.krate.kotlinx.optional.KotlinxDelegateFactory
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KType
 import kotlin.reflect.typeOf
@@ -14,13 +15,18 @@ import kotlin.reflect.typeOf
  * This instance will be serialized using kotlinx.serialization.
  */
 @OptIn(ExperimentalStdlibApi::class)
-public inline fun <reified T : Any> Krate.kotlinxPref(key: String): ReadWriteProperty<Krate, T?> {
+public inline fun <reified T : Any> Krate.kotlinxPref(
+    key: String,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
     return kotlinxPrefImpl(key, typeOf<T>())
 }
 
 @PublishedApi
-internal fun <T : Any> Krate.kotlinxPrefImpl(key: String, type: KType): ReadWriteProperty<Krate, T?> {
-    return KotlinxDelegate(key, type)
+internal fun <T : Any> Krate.kotlinxPrefImpl(
+    key: String,
+    type: KType,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
+    return KotlinxDelegateFactory(key, type)
 }
 
 /**
@@ -28,11 +34,18 @@ internal fun <T : Any> Krate.kotlinxPrefImpl(key: String, type: KType): ReadWrit
  * This instance will be serialized using kotlinx.serialization.
  */
 @OptIn(ExperimentalStdlibApi::class)
-public inline fun <reified T : Any> Krate.kotlinxPref(key: String, defaultValue: T): ReadWriteProperty<Krate, T> {
+public inline fun <reified T : Any> Krate.kotlinxPref(
+    key: String,
+    defaultValue: T,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
     return kotlinxPrefImpl(key, defaultValue, typeOf<T>())
 }
 
 @PublishedApi
-internal fun <T : Any> Krate.kotlinxPrefImpl(key: String, defaultValue: T, type: KType): ReadWriteProperty<Krate, T> {
-    return KotlinxDelegateWithDefault(key, defaultValue, type)
+internal fun <T : Any> Krate.kotlinxPrefImpl(
+    key: String,
+    defaultValue: T,
+    type: KType,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
+    return KotlinxDelegateWithDefaultFactory(key, defaultValue, type)
 }
diff --git a/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/default/KotlinxDelegateWithDefault.kt b/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/default/KotlinxDelegateWithDefault.kt
index 5e080fc..0a467c1 100644
--- a/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/default/KotlinxDelegateWithDefault.kt
+++ b/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/default/KotlinxDelegateWithDefault.kt
@@ -1,38 +1,43 @@
 package hu.autsoft.krate.kotlinx.default
 
 import hu.autsoft.krate.Krate
+import hu.autsoft.krate.kotlinx.internalJson
 import hu.autsoft.krate.kotlinx.util.edit
 import kotlinx.serialization.KSerializer
-import kotlinx.serialization.json.Json
 import kotlinx.serialization.serializer
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 import kotlin.reflect.KType
 
-
-internal class KotlinxDelegateWithDefault<T : Any>(
-        private val key: String,
-        private val default: T,
-        private val type: KType,
+private class KotlinxDelegateWithDefault<T : Any>(
+    private val key: String,
+    private val default: T,
+    private val serializer: KSerializer<T>,
 ) : ReadWriteProperty<Krate, T> {
-
-    @Suppress("UNCHECKED_CAST")
-    private inline val serializer: KSerializer<T>
-        get() = Json.serializersModule.serializer(type) as KSerializer<T>
-
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): T {
         if (!thisRef.sharedPreferences.contains(key)) {
             return default
         }
-
         val string = requireNotNull(thisRef.sharedPreferences.getString(key, null))
-        return Json.decodeFromString(serializer, string)
+        return thisRef.internalJson.decodeFromString(serializer, string)
     }
 
     override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T) {
         thisRef.sharedPreferences.edit {
-            putString(key, Json.encodeToString(serializer, value))
+            putString(key, thisRef.internalJson.encodeToString(serializer, value))
         }
     }
+}
 
+internal class KotlinxDelegateWithDefaultFactory<T : Any>(
+    private val key: String,
+    private val default: T,
+    private val type: KType,
+) : PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
+    override fun provideDelegate(thisRef: Krate, property: KProperty<*>): ReadWriteProperty<Krate, T> {
+        @Suppress("UNCHECKED_CAST")
+        val serializer = thisRef.internalJson.serializersModule.serializer(type) as KSerializer<T>
+        return KotlinxDelegateWithDefault(key, default, serializer)
+    }
 }
diff --git a/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/optional/KotlinxDelegate.kt b/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/optional/KotlinxDelegate.kt
index e41e1e8..bbf269f 100644
--- a/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/optional/KotlinxDelegate.kt
+++ b/krate-kotlinx/src/main/kotlin/hu/autsoft/krate/kotlinx/optional/KotlinxDelegate.kt
@@ -1,30 +1,26 @@
 package hu.autsoft.krate.kotlinx.optional
 
 import hu.autsoft.krate.Krate
+import hu.autsoft.krate.kotlinx.internalJson
 import hu.autsoft.krate.kotlinx.util.edit
 import kotlinx.serialization.KSerializer
-import kotlinx.serialization.json.Json
 import kotlinx.serialization.serializer
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 import kotlin.reflect.KType
 
 
-internal class KotlinxDelegate<T : Any>(
-        private val key: String,
-        private val type: KType,
+private class KotlinxDelegate<T : Any>(
+    private val key: String,
+    private val serializer: KSerializer<T>,
 ) : ReadWriteProperty<Krate, T?> {
-
-    @Suppress("UNCHECKED_CAST")
-    private inline val serializer: KSerializer<T>
-        get() = Json.serializersModule.serializer(type) as KSerializer<T>
-
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
         return if (!thisRef.sharedPreferences.contains(key)) {
             null
         } else {
             val string = requireNotNull(thisRef.sharedPreferences.getString(key, null))
-            Json.decodeFromString(serializer, string)
+            thisRef.internalJson.decodeFromString(serializer, string)
         }
     }
 
@@ -35,9 +31,19 @@ internal class KotlinxDelegate<T : Any>(
             }
         } else {
             thisRef.sharedPreferences.edit {
-                putString(key, Json.encodeToString(serializer, value))
+                putString(key, thisRef.internalJson.encodeToString(serializer, value))
             }
         }
     }
+}
 
+internal class KotlinxDelegateFactory<T : Any>(
+    private val key: String,
+    private val type: KType,
+) : PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
+    override fun provideDelegate(thisRef: Krate, property: KProperty<*>): ReadWriteProperty<Krate, T?> {
+        @Suppress("UNCHECKED_CAST")
+        val serializer = thisRef.internalJson.serializersModule.serializer(type) as KSerializer<T>
+        return KotlinxDelegate(key, serializer)
+    }
 }
diff --git a/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/KotlinxTestKrate.kt b/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/KotlinxTestKrate.kt
index 9b2486d..315797b 100644
--- a/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/KotlinxTestKrate.kt
+++ b/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/KotlinxTestKrate.kt
@@ -28,14 +28,14 @@ internal class KotlinxTestKrate(context: Context) : SimpleKrate(context) {
 
     var validatedValue: TestModel
             by kotlinxPref(key = "validatedValue", defaultValue = DEFAULT_SIMPLE_VALUE)
-                    .validate { newValue ->
-                        newValue.x < newValue.y // arbitrary rule
-                    }
+                .validate { newValue ->
+                    newValue.x < newValue.y // arbitrary rule
+                }
 
     var validatedOptionalValue: List<TestModel>?
             by kotlinxPref<List<TestModel>>(key = "validatedOptionalValue")
-                    .validate { newValue ->
-                        newValue.isNullOrEmpty().not() // arbitrary rule
-                    }
+                .validate { newValue ->
+                    newValue.isNullOrEmpty().not() // arbitrary rule
+                }
 
 }
diff --git a/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/KotlinxDelegateTest.kt b/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/KotlinxDelegateTest.kt
index aab0bde..f36fd1f 100644
--- a/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/KotlinxDelegateTest.kt
+++ b/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/KotlinxDelegateTest.kt
@@ -47,9 +47,9 @@ internal class KotlinxDelegateTest {
     @Test
     fun testSetListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValues = list
@@ -60,9 +60,9 @@ internal class KotlinxDelegateTest {
     @Test
     fun testRemoveListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValues = list
diff --git a/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/KotlinxDelegateWithDefaultTest.kt b/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/KotlinxDelegateWithDefaultTest.kt
index af7b754..a5f5bca 100644
--- a/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/KotlinxDelegateWithDefaultTest.kt
+++ b/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/KotlinxDelegateWithDefaultTest.kt
@@ -37,9 +37,9 @@ internal class KotlinxDelegateWithDefaultTest {
     @Test
     fun testListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValuesWithDefault = list
diff --git a/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/ValidatedKotlinxDelegateTest.kt b/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/ValidatedKotlinxDelegateTest.kt
index 06bad97..cbb6c0d 100644
--- a/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/ValidatedKotlinxDelegateTest.kt
+++ b/krate-kotlinx/src/test/java/hu/autsoft/krate/kotlinx/test/ValidatedKotlinxDelegateTest.kt
@@ -36,8 +36,8 @@ internal class ValidatedKotlinxDelegateTest {
     @Test
     fun testValidOptionalValue() {
         val newValue = listOf(
-                TestModel(20, 21.0, ""),
-                TestModel(10, 5.0, "")
+            TestModel(20, 21.0, ""),
+            TestModel(10, 5.0, "")
         )
 
         krate.validatedOptionalValue = newValue
diff --git a/krate-moshi-codegen/build.gradle b/krate-moshi-codegen/build.gradle
index 79a48d5..e5d0326 100644
--- a/krate-moshi-codegen/build.gradle
+++ b/krate-moshi-codegen/build.gradle
@@ -12,10 +12,6 @@ android {
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
-    sourceSets {
-        main.java.srcDirs += 'src/main/kotlin'
-    }
-
     buildFeatures {
         buildConfig false
     }
@@ -33,7 +29,6 @@ tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
 dependencies {
     implementation project(':krate')
     api project(':krate-moshi-core')
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
 
     api "com.squareup.moshi:moshi:$moshi_version"
     kaptTest "com.squareup.moshi:moshi-kotlin-codegen:$moshi_version"
diff --git a/krate-moshi-codegen/src/main/kotlin/hu/autsoft/krate/moshi/DefaultMoshiInstance.kt b/krate-moshi-codegen/src/main/kotlin/hu/autsoft/krate/moshi/DefaultMoshiInstance.kt
index 0d7008f..ca47f43 100644
--- a/krate-moshi-codegen/src/main/kotlin/hu/autsoft/krate/moshi/DefaultMoshiInstance.kt
+++ b/krate-moshi-codegen/src/main/kotlin/hu/autsoft/krate/moshi/DefaultMoshiInstance.kt
@@ -4,5 +4,5 @@ import com.squareup.moshi.Moshi
 
 internal val defaultMoshi by lazy {
     Moshi.Builder()
-            .build()
+        .build()
 }
diff --git a/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/MoshiTestKrate.kt b/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/MoshiTestKrate.kt
index f945413..800ff45 100644
--- a/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/MoshiTestKrate.kt
+++ b/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/MoshiTestKrate.kt
@@ -28,14 +28,14 @@ internal class MoshiTestKrate(context: Context) : SimpleKrate(context) {
 
     var validatedValue: TestModel
             by moshiPref(key = "validatedValue", defaultValue = DEFAULT_SIMPLE_VALUE)
-                    .validate { newValue ->
-                        newValue.x < newValue.y // arbitrary rule
-                    }
+                .validate { newValue ->
+                    newValue.x < newValue.y // arbitrary rule
+                }
 
     var validatedOptionalValue: List<TestModel>?
             by moshiPref<List<TestModel>>(key = "validatedOptionalValue")
-                    .validate { newValue ->
-                        newValue.isNullOrEmpty().not() // arbitrary rule
-                    }
+                .validate { newValue ->
+                    newValue.isNullOrEmpty().not() // arbitrary rule
+                }
 
 }
diff --git a/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/CustomMoshiInstanceTest.kt b/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/CustomMoshiInstanceTest.kt
index 567a961..d238322 100644
--- a/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/CustomMoshiInstanceTest.kt
+++ b/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/CustomMoshiInstanceTest.kt
@@ -81,7 +81,7 @@ internal class CustomMoshiInstanceTest {
 
     private fun createCustomTestMoshi(): Moshi {
         return Moshi.Builder()
-                .build()
+            .build()
     }
 
 }
diff --git a/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateTest.kt b/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateTest.kt
index f4264f6..524ea87 100644
--- a/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateTest.kt
+++ b/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateTest.kt
@@ -47,9 +47,9 @@ internal class MoshiDelegateTest {
     @Test
     fun testSetListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValues = list
@@ -60,9 +60,9 @@ internal class MoshiDelegateTest {
     @Test
     fun testRemoveListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValues = list
diff --git a/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateWithDefaultTest.kt b/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateWithDefaultTest.kt
index de0293b..7b963c2 100644
--- a/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateWithDefaultTest.kt
+++ b/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateWithDefaultTest.kt
@@ -37,9 +37,9 @@ internal class MoshiDelegateWithDefaultTest {
     @Test
     fun testListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValuesWithDefault = list
diff --git a/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/ValidatedMoshiDelegateTest.kt b/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/ValidatedMoshiDelegateTest.kt
index eb82bd4..8724b5d 100644
--- a/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/ValidatedMoshiDelegateTest.kt
+++ b/krate-moshi-codegen/src/test/java/hu/autsoft/krate/moshi/test/ValidatedMoshiDelegateTest.kt
@@ -41,8 +41,8 @@ internal class ValidatedMoshiDelegateTest {
     @Test
     fun testValidOptionalValue() {
         val newValue = listOf(
-                TestModel(20, 21.0, ""),
-                TestModel(10, 5.0, "")
+            TestModel(20, 21.0, ""),
+            TestModel(10, 5.0, "")
         )
 
         krate.validatedOptionalValue = newValue
diff --git a/krate-moshi-core/build.gradle b/krate-moshi-core/build.gradle
index 4c00973..934842a 100644
--- a/krate-moshi-core/build.gradle
+++ b/krate-moshi-core/build.gradle
@@ -11,10 +11,6 @@ android {
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
-    sourceSets {
-        main.java.srcDirs += 'src/main/kotlin'
-    }
-
     buildFeatures {
         buildConfig false
     }
@@ -32,7 +28,6 @@ tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
 
 dependencies {
     implementation project(':krate')
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
 
     compileOnly project(':krate-moshi-stub')
 
diff --git a/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/Functions.kt b/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/Functions.kt
index ff22a6b..fc18755 100644
--- a/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/Functions.kt
+++ b/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/Functions.kt
@@ -3,9 +3,10 @@
 package hu.autsoft.krate.moshi
 
 import hu.autsoft.krate.Krate
-import hu.autsoft.krate.moshi.default.MoshiDelegateWithDefault
-import hu.autsoft.krate.moshi.optional.MoshiDelegate
+import hu.autsoft.krate.moshi.default.MoshiDelegateWithDefaultFactory
+import hu.autsoft.krate.moshi.optional.MoshiDelegateFactory
 import java.lang.reflect.Type
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.javaType
 import kotlin.reflect.typeOf
@@ -15,13 +16,18 @@ import kotlin.reflect.typeOf
  * This instance will be serialized using Moshi.
  */
 @OptIn(ExperimentalStdlibApi::class)
-public inline fun <reified T : Any> Krate.moshiPref(key: String): ReadWriteProperty<Krate, T?> {
+public inline fun <reified T : Any> Krate.moshiPref(
+    key: String,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
     return moshiPrefImpl(key, typeOf<T>().javaType)
 }
 
 @PublishedApi
-internal fun <T : Any> Krate.moshiPrefImpl(key: String, type: Type): ReadWriteProperty<Krate, T?> {
-    return MoshiDelegate(key, type)
+internal fun <T : Any> Krate.moshiPrefImpl(
+    key: String,
+    type: Type,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
+    return MoshiDelegateFactory(key, type)
 }
 
 /**
@@ -29,11 +35,18 @@ internal fun <T : Any> Krate.moshiPrefImpl(key: String, type: Type): ReadWritePr
  * This instance will be serialized using Moshi.
  */
 @OptIn(ExperimentalStdlibApi::class)
-public inline fun <reified T : Any> Krate.moshiPref(key: String, defaultValue: T): ReadWriteProperty<Krate, T> {
+public inline fun <reified T : Any> Krate.moshiPref(
+    key: String,
+    defaultValue: T,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
     return moshiPrefImpl(key, defaultValue, typeOf<T>().javaType)
 }
 
 @PublishedApi
-internal fun <T : Any> Krate.moshiPrefImpl(key: String, defaultValue: T, type: Type): ReadWriteProperty<Krate, T> {
-    return MoshiDelegateWithDefault(key, defaultValue, type)
+internal fun <T : Any> Krate.moshiPrefImpl(
+    key: String,
+    defaultValue: T,
+    type: Type,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
+    return MoshiDelegateWithDefaultFactory(key, defaultValue, type)
 }
diff --git a/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/MoshiInstances.kt b/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/MoshiInstances.kt
index 7284f1e..6736288 100644
--- a/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/MoshiInstances.kt
+++ b/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/MoshiInstances.kt
@@ -7,7 +7,12 @@ internal val moshiInstances: MutableMap<Krate, Moshi> = mutableMapOf<Krate, Mosh
     try {
         defaultMoshi
     } catch (e: Throwable) {
-        throw IllegalStateException("Do not use krate-moshi-core directly. Either krate-moshi-codegen (if you only use Moshi with codegen) or krate-moshi-reflect (if you use Moshi via reflection at all) should be included as a dependency!", e)
+        throw IllegalStateException(
+            message = "Do not use krate-moshi-core directly. Either krate-moshi-codegen (if you only use Moshi" +
+                    " with codegen) or krate-moshi-reflect (if you use Moshi via reflection at all) should be" +
+                    " included as a dependency!",
+            cause = e
+        )
     }
 }
 
diff --git a/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/ValidatedFunctions.kt b/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/ValidatedFunctions.kt
index 48c6bbc..009736d 100644
--- a/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/ValidatedFunctions.kt
+++ b/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/ValidatedFunctions.kt
@@ -4,10 +4,11 @@ package hu.autsoft.krate.moshi
 
 import hu.autsoft.krate.Krate
 import hu.autsoft.krate.internal.InternalKrateApi
-import hu.autsoft.krate.moshi.default.MoshiDelegateWithDefault
-import hu.autsoft.krate.moshi.optional.MoshiDelegate
-import hu.autsoft.krate.validation.ValidatedPreferenceDelegate
+import hu.autsoft.krate.moshi.default.MoshiDelegateWithDefaultFactory
+import hu.autsoft.krate.moshi.optional.MoshiDelegateFactory
+import hu.autsoft.krate.validation.ValidatedPreferenceDelegateFactory
 import java.lang.reflect.Type
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.javaType
 import kotlin.reflect.typeOf
@@ -18,27 +19,27 @@ import kotlin.reflect.typeOf
  */
 @OptIn(ExperimentalStdlibApi::class)
 @Deprecated(
-        message = "Use .validate {} on a moshiPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.moshiPref<T>(key).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a moshiPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.moshiPref<T>(key).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public inline fun <reified T : Any> Krate.moshiPref(
-        key: String,
-        noinline isValid: (newValue: T?) -> Boolean,
-): ReadWriteProperty<Krate, T?> {
+    key: String,
+    noinline isValid: (newValue: T?) -> Boolean,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
     return moshiPrefImpl(key, typeOf<T>().javaType, isValid)
 }
 
 @PublishedApi
 internal fun <T : Any> Krate.moshiPrefImpl(
-        key: String,
-        type: Type,
-        isValid: (newValue: T?) -> Boolean,
-): ReadWriteProperty<Krate, T?> {
-    return ValidatedPreferenceDelegate(MoshiDelegate(key, type), isValid)
+    key: String,
+    type: Type,
+    isValid: (newValue: T?) -> Boolean,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
+    return ValidatedPreferenceDelegateFactory(MoshiDelegateFactory(key, type), isValid)
 }
 
 /**
@@ -48,27 +49,27 @@ internal fun <T : Any> Krate.moshiPrefImpl(
  */
 @OptIn(ExperimentalStdlibApi::class)
 @Deprecated(
-        message = "Use .validate {} on a moshiPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.moshiPref(key, defaultValue).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a moshiPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.moshiPref(key, defaultValue).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public inline fun <reified T : Any> Krate.moshiPref(
-        key: String,
-        defaultValue: T,
-        noinline isValid: (newValue: T) -> Boolean,
-): ReadWriteProperty<Krate, T> {
+    key: String,
+    defaultValue: T,
+    noinline isValid: (newValue: T) -> Boolean,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
     return moshiPrefImpl(key, defaultValue, typeOf<T>().javaType, isValid)
 }
 
 @PublishedApi
 internal fun <T : Any> Krate.moshiPrefImpl(
-        key: String,
-        defaultValue: T,
-        type: Type,
-        isValid: (newValue: T) -> Boolean,
-): ReadWriteProperty<Krate, T> {
-    return ValidatedPreferenceDelegate(MoshiDelegateWithDefault(key, defaultValue, type), isValid)
+    key: String,
+    defaultValue: T,
+    type: Type,
+    isValid: (newValue: T) -> Boolean,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
+    return ValidatedPreferenceDelegateFactory(MoshiDelegateWithDefaultFactory(key, defaultValue, type), isValid)
 }
diff --git a/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/default/MoshiDelegateWithDefault.kt b/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/default/MoshiDelegateWithDefault.kt
index e71304d..7ebbd06 100644
--- a/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/default/MoshiDelegateWithDefault.kt
+++ b/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/default/MoshiDelegateWithDefault.kt
@@ -1,34 +1,42 @@
 package hu.autsoft.krate.moshi.default
 
+import com.squareup.moshi.JsonAdapter
 import hu.autsoft.krate.Krate
 import hu.autsoft.krate.moshi.realMoshiInstance
 import hu.autsoft.krate.moshi.util.edit
 import java.lang.reflect.Type
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 
-internal class MoshiDelegateWithDefault<T : Any>(
-        private val key: String,
-        private val default: T,
-        private val type: Type,
+private class MoshiDelegateWithDefault<T : Any>(
+    private val key: String,
+    private val default: T,
+    private val adapter: JsonAdapter<T>,
 ) : ReadWriteProperty<Krate, T> {
-
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): T {
         if (!thisRef.sharedPreferences.contains(key)) {
             return default
         }
-
         val string = requireNotNull(thisRef.sharedPreferences.getString(key, null))
-        val adapter = thisRef.realMoshiInstance.adapter<T>(type)
         return requireNotNull(adapter.fromJson(string))
     }
 
     override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T) {
         thisRef.sharedPreferences.edit {
-            val adapter = thisRef.realMoshiInstance.adapter<T>(type)
             putString(key, adapter.toJson(value))
         }
     }
+}
 
+internal class MoshiDelegateWithDefaultFactory<T : Any>(
+    private val key: String,
+    private val default: T,
+    private val type: Type,
+) : PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
+    override fun provideDelegate(thisRef: Krate, property: KProperty<*>): ReadWriteProperty<Krate, T> {
+        val adapter = thisRef.realMoshiInstance.adapter<T>(type)
+        return MoshiDelegateWithDefault(key, default, adapter)
+    }
 }
diff --git a/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/optional/MoshiDelegate.kt b/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/optional/MoshiDelegate.kt
index d758971..ee70320 100644
--- a/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/optional/MoshiDelegate.kt
+++ b/krate-moshi-core/src/main/kotlin/hu/autsoft/krate/moshi/optional/MoshiDelegate.kt
@@ -1,24 +1,23 @@
 package hu.autsoft.krate.moshi.optional
 
+import com.squareup.moshi.JsonAdapter
 import hu.autsoft.krate.Krate
 import hu.autsoft.krate.moshi.realMoshiInstance
 import hu.autsoft.krate.moshi.util.edit
 import java.lang.reflect.Type
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
-
-internal class MoshiDelegate<T : Any>(
-        private val key: String,
-        private val type: Type,
+private class MoshiDelegate<T : Any>(
+    private val key: String,
+    private val adapter: JsonAdapter<T>,
 ) : ReadWriteProperty<Krate, T?> {
-
     override fun getValue(thisRef: Krate, property: KProperty<*>): T? {
         return if (!thisRef.sharedPreferences.contains(key)) {
             null
         } else {
             val string = requireNotNull(thisRef.sharedPreferences.getString(key, null))
-            val adapter = thisRef.realMoshiInstance.adapter<T?>(type)
             adapter.fromJson(string)
         }
     }
@@ -30,10 +29,18 @@ internal class MoshiDelegate<T : Any>(
             }
         } else {
             thisRef.sharedPreferences.edit {
-                val adapter = thisRef.realMoshiInstance.adapter<T?>(type)
                 putString(key, adapter.toJson(value))
             }
         }
     }
+}
 
+internal class MoshiDelegateFactory<T : Any>(
+    private val key: String,
+    private val type: Type,
+) : PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T?>> {
+    override fun provideDelegate(thisRef: Krate, property: KProperty<*>): ReadWriteProperty<Krate, T?> {
+        val adapter = thisRef.realMoshiInstance.adapter<T?>(type)
+        return MoshiDelegate(key, adapter)
+    }
 }
diff --git a/krate-moshi-reflect/build.gradle b/krate-moshi-reflect/build.gradle
index ce61f3f..a5b3f6b 100644
--- a/krate-moshi-reflect/build.gradle
+++ b/krate-moshi-reflect/build.gradle
@@ -11,10 +11,6 @@ android {
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
-    sourceSets {
-        main.java.srcDirs += 'src/main/kotlin'
-    }
-
     buildFeatures {
         buildConfig false
     }
@@ -32,7 +28,6 @@ tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
 dependencies {
     implementation project(':krate')
     api project(':krate-moshi-core')
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
 
     api "com.squareup.moshi:moshi:$moshi_version"
     api "com.squareup.moshi:moshi-kotlin:$moshi_version"
diff --git a/krate-moshi-reflect/src/main/kotlin/hu/autsoft/krate/moshi/DefaultMoshiInstance.kt b/krate-moshi-reflect/src/main/kotlin/hu/autsoft/krate/moshi/DefaultMoshiInstance.kt
index 6d1e210..29bbff0 100644
--- a/krate-moshi-reflect/src/main/kotlin/hu/autsoft/krate/moshi/DefaultMoshiInstance.kt
+++ b/krate-moshi-reflect/src/main/kotlin/hu/autsoft/krate/moshi/DefaultMoshiInstance.kt
@@ -5,6 +5,6 @@ import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
 
 internal val defaultMoshi by lazy {
     Moshi.Builder()
-            .add(KotlinJsonAdapterFactory())
-            .build()
+        .add(KotlinJsonAdapterFactory())
+        .build()
 }
diff --git a/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/MoshiTestKrate.kt b/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/MoshiTestKrate.kt
index f945413..800ff45 100644
--- a/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/MoshiTestKrate.kt
+++ b/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/MoshiTestKrate.kt
@@ -28,14 +28,14 @@ internal class MoshiTestKrate(context: Context) : SimpleKrate(context) {
 
     var validatedValue: TestModel
             by moshiPref(key = "validatedValue", defaultValue = DEFAULT_SIMPLE_VALUE)
-                    .validate { newValue ->
-                        newValue.x < newValue.y // arbitrary rule
-                    }
+                .validate { newValue ->
+                    newValue.x < newValue.y // arbitrary rule
+                }
 
     var validatedOptionalValue: List<TestModel>?
             by moshiPref<List<TestModel>>(key = "validatedOptionalValue")
-                    .validate { newValue ->
-                        newValue.isNullOrEmpty().not() // arbitrary rule
-                    }
+                .validate { newValue ->
+                    newValue.isNullOrEmpty().not() // arbitrary rule
+                }
 
 }
diff --git a/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/CustomMoshiInstanceTest.kt b/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/CustomMoshiInstanceTest.kt
index e1691d4..6080a46 100644
--- a/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/CustomMoshiInstanceTest.kt
+++ b/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/CustomMoshiInstanceTest.kt
@@ -82,8 +82,8 @@ internal class CustomMoshiInstanceTest {
 
     private fun createCustomTestMoshi(): Moshi {
         return Moshi.Builder()
-                .add(KotlinJsonAdapterFactory())
-                .build()
+            .add(KotlinJsonAdapterFactory())
+            .build()
     }
 
 }
diff --git a/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateTest.kt b/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateTest.kt
index f4264f6..524ea87 100644
--- a/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateTest.kt
+++ b/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateTest.kt
@@ -47,9 +47,9 @@ internal class MoshiDelegateTest {
     @Test
     fun testSetListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValues = list
@@ -60,9 +60,9 @@ internal class MoshiDelegateTest {
     @Test
     fun testRemoveListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValues = list
diff --git a/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateWithDefaultTest.kt b/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateWithDefaultTest.kt
index de0293b..7b963c2 100644
--- a/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateWithDefaultTest.kt
+++ b/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/MoshiDelegateWithDefaultTest.kt
@@ -37,9 +37,9 @@ internal class MoshiDelegateWithDefaultTest {
     @Test
     fun testListOfValues() {
         val list = listOf(
-                TestModel(x = 42, y = 3.141592, z = "shibboleth"),
-                TestModel(x = 13, y = 6.283185, z = "signal"),
-                TestModel(x = 34, y = 2.718182, z = "bingo")
+            TestModel(x = 42, y = 3.141592, z = "shibboleth"),
+            TestModel(x = 13, y = 6.283185, z = "signal"),
+            TestModel(x = 34, y = 2.718182, z = "bingo")
         )
 
         krate.listOfValuesWithDefault = list
diff --git a/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/ValidatedMoshiDelegateTest.kt b/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/ValidatedMoshiDelegateTest.kt
index 4f761a6..43e2fba 100644
--- a/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/ValidatedMoshiDelegateTest.kt
+++ b/krate-moshi-reflect/src/test/java/hu/autsoft/krate/moshi/test/ValidatedMoshiDelegateTest.kt
@@ -36,8 +36,8 @@ internal class ValidatedMoshiDelegateTest {
     @Test
     fun testValidOptionalValue() {
         val newValue = listOf(
-                TestModel(20, 21.0, ""),
-                TestModel(10, 5.0, "")
+            TestModel(20, 21.0, ""),
+            TestModel(10, 5.0, "")
         )
 
         krate.validatedOptionalValue = newValue
diff --git a/krate-moshi-stub/build.gradle b/krate-moshi-stub/build.gradle
index 3331865..47cf44b 100644
--- a/krate-moshi-stub/build.gradle
+++ b/krate-moshi-stub/build.gradle
@@ -11,10 +11,6 @@ android {
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
-    sourceSets {
-        main.java.srcDirs += 'src/main/kotlin'
-    }
-
     buildFeatures {
         buildConfig false
     }
@@ -31,7 +27,6 @@ tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
 
 dependencies {
     implementation project(':krate')
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
 
     api "com.squareup.moshi:moshi:$moshi_version"
 }
diff --git a/krate/build.gradle b/krate/build.gradle
index 4b1ac89..18fde1d 100644
--- a/krate/build.gradle
+++ b/krate/build.gradle
@@ -11,10 +11,6 @@ android {
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
-    sourceSets {
-        main.java.srcDirs += 'src/main/kotlin'
-    }
-
     buildFeatures {
         buildConfig false
     }
@@ -26,12 +22,12 @@ tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
                 '-progressive',
                 '-Xexplicit-api=strict',
                 '-Xopt-in=kotlin.RequiresOptIn',
+                '-Xopt-in=hu.autsoft.krate.internal.InternalKrateApi',
         ]
     }
 }
 
 dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
     implementation 'androidx.preference:preference-ktx:1.1.1'
 
     testImplementation "junit:junit:$junit_version"
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/SimpleKrate.kt b/krate/src/main/kotlin/hu/autsoft/krate/SimpleKrate.kt
index 2945fb3..e6d04a5 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/SimpleKrate.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/SimpleKrate.kt
@@ -13,8 +13,8 @@ import androidx.preference.PreferenceManager
  * [PreferenceManager.getDefaultSharedPreferences].
  */
 public abstract class SimpleKrate(
-        context: Context,
-        name: String? = null,
+    context: Context,
+    name: String? = null,
 ) : Krate {
 
     public override val sharedPreferences: SharedPreferences = when (name) {
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/ValidatedFunctions.kt b/krate/src/main/kotlin/hu/autsoft/krate/ValidatedFunctions.kt
index 56d70ac..1e1d27c 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/ValidatedFunctions.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/ValidatedFunctions.kt
@@ -23,16 +23,16 @@ import kotlin.properties.ReadWriteProperty
  * an [IllegalArgumentException] will be thrown.
  */
 @Deprecated(
-        message = "Use .validate {} on a floatPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.floatPref(key).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a floatPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.floatPref(key).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public fun Krate.floatPref(
-        key: String,
-        isValid: (newValue: Float?) -> Boolean,
+    key: String,
+    isValid: (newValue: Float?) -> Boolean,
 ): ReadWriteProperty<Krate, Float?> {
     return ValidatedPreferenceDelegate(FloatDelegate(key), isValid)
 }
@@ -44,17 +44,17 @@ public fun Krate.floatPref(
  * an [IllegalArgumentException] will be thrown.
  */
 @Deprecated(
-        message = "Use .validate {} on a floatPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.floatPref(key, defaultValue).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a floatPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.floatPref(key, defaultValue).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public fun Krate.floatPref(
-        key: String,
-        defaultValue: Float,
-        isValid: (newValue: Float) -> Boolean,
+    key: String,
+    defaultValue: Float,
+    isValid: (newValue: Float) -> Boolean,
 ): ReadWriteProperty<Krate, Float> {
     return ValidatedPreferenceDelegate(FloatDelegateWithDefault(key, defaultValue), isValid)
 }
@@ -66,16 +66,16 @@ public fun Krate.floatPref(
  * an [IllegalArgumentException] will be thrown.
  */
 @Deprecated(
-        message = "Use .validate {} on an intPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.intPref(key).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on an intPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.intPref(key).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public fun Krate.intPref(
-        key: String,
-        isValid: (newValue: Int?) -> Boolean,
+    key: String,
+    isValid: (newValue: Int?) -> Boolean,
 ): ReadWriteProperty<Krate, Int?> {
     return ValidatedPreferenceDelegate(IntDelegate(key), isValid)
 }
@@ -87,17 +87,17 @@ public fun Krate.intPref(
  * an [IllegalArgumentException] will be thrown.
  */
 @Deprecated(
-        message = "Use .validate {} on an intPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.intPref(key, defaultValue).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on an intPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.intPref(key, defaultValue).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public fun Krate.intPref(
-        key: String,
-        defaultValue: Int,
-        isValid: (newValue: Int) -> Boolean,
+    key: String,
+    defaultValue: Int,
+    isValid: (newValue: Int) -> Boolean,
 ): ReadWriteProperty<Krate, Int> {
     return ValidatedPreferenceDelegate(IntDelegateWithDefault(key, defaultValue), isValid)
 }
@@ -109,16 +109,16 @@ public fun Krate.intPref(
  * an [IllegalArgumentException] will be thrown.
  */
 @Deprecated(
-        message = "Use .validate {} on a longPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.longPref(key).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a longPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.longPref(key).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public fun Krate.longPref(
-        key: String,
-        isValid: (newValue: Long?) -> Boolean,
+    key: String,
+    isValid: (newValue: Long?) -> Boolean,
 ): ReadWriteProperty<Krate, Long?> {
     return ValidatedPreferenceDelegate(LongDelegate(key), isValid)
 }
@@ -130,17 +130,17 @@ public fun Krate.longPref(
  * an [IllegalArgumentException] will be thrown.
  */
 @Deprecated(
-        message = "Use .validate {} on a longPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.longPref(key, defaultValue).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a longPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.longPref(key, defaultValue).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public fun Krate.longPref(
-        key: String,
-        defaultValue: Long,
-        isValid: (newValue: Long) -> Boolean,
+    key: String,
+    defaultValue: Long,
+    isValid: (newValue: Long) -> Boolean,
 ): ReadWriteProperty<Krate, Long> {
     return ValidatedPreferenceDelegate(LongDelegateWithDefault(key, defaultValue), isValid)
 }
@@ -152,16 +152,16 @@ public fun Krate.longPref(
  * an [IllegalArgumentException] will be thrown.
  */
 @Deprecated(
-        message = "Use .validate {} on a stringPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.stringPref(key).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a stringPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.stringPref(key).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public fun Krate.stringPref(
-        key: String,
-        isValid: (newValue: String?) -> Boolean,
+    key: String,
+    isValid: (newValue: String?) -> Boolean,
 ): ReadWriteProperty<Krate, String?> {
     return ValidatedPreferenceDelegate(StringDelegate(key), isValid)
 }
@@ -173,17 +173,17 @@ public fun Krate.stringPref(
  * an [IllegalArgumentException] will be thrown.
  */
 @Deprecated(
-        message = "Use .validate {} on a stringPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.stringPref(key, defaultValue).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a stringPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.stringPref(key, defaultValue).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public fun Krate.stringPref(
-        key: String,
-        defaultValue: String,
-        isValid: (newValue: String) -> Boolean,
+    key: String,
+    defaultValue: String,
+    isValid: (newValue: String) -> Boolean,
 ): ReadWriteProperty<Krate, String> {
     return ValidatedPreferenceDelegate(StringDelegateWithDefault(key, defaultValue), isValid)
 }
@@ -195,16 +195,16 @@ public fun Krate.stringPref(
  * an [IllegalArgumentException] will be thrown.
  */
 @Deprecated(
-        message = "Use .validate {} on a stringSetPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.stringSetPref(key).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a stringSetPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.stringSetPref(key).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public fun Krate.stringSetPref(
-        key: String,
-        isValid: (newValue: Set<String>?) -> Boolean,
+    key: String,
+    isValid: (newValue: Set<String>?) -> Boolean,
 ): ReadWriteProperty<Krate, Set<String>?> {
     return ValidatedPreferenceDelegate(StringSetDelegate(key), isValid)
 }
@@ -216,17 +216,17 @@ public fun Krate.stringSetPref(
  * an [IllegalArgumentException] will be thrown.
  */
 @Deprecated(
-        message = "Use .validate {} on a stringSetPref instead",
-        level = DeprecationLevel.WARNING,
-        replaceWith = ReplaceWith(
-                "this.stringSetPref(key, defaultValue).validate(isValid)",
-                imports = arrayOf("hu.autsoft.krate.validation.validate"),
-        ),
+    message = "Use .validate {} on a stringSetPref instead",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith(
+        "this.stringSetPref(key, defaultValue).validate(isValid)",
+        imports = arrayOf("hu.autsoft.krate.validation.validate"),
+    ),
 )
 public fun Krate.stringSetPref(
-        key: String,
-        defaultValue: Set<String>,
-        isValid: (newValue: Set<String>) -> Boolean,
+    key: String,
+    defaultValue: Set<String>,
+    isValid: (newValue: Set<String>) -> Boolean,
 ): ReadWriteProperty<Krate, Set<String>> {
     return ValidatedPreferenceDelegate(StringSetDelegateWithDefault(key, defaultValue), isValid)
 }
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/default/BooleanDelegateWithDefault.kt b/krate/src/main/kotlin/hu/autsoft/krate/default/BooleanDelegateWithDefault.kt
index 9fadb17..2586b44 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/default/BooleanDelegateWithDefault.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/default/BooleanDelegateWithDefault.kt
@@ -6,8 +6,8 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class BooleanDelegateWithDefault(
-        private val key: String,
-        private val default: Boolean,
+    private val key: String,
+    private val default: Boolean,
 ) : ReadWriteProperty<Krate, Boolean> {
 
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): Boolean {
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/default/FloatDelegateWithDefault.kt b/krate/src/main/kotlin/hu/autsoft/krate/default/FloatDelegateWithDefault.kt
index 262bf3c..f7498d0 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/default/FloatDelegateWithDefault.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/default/FloatDelegateWithDefault.kt
@@ -6,8 +6,8 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class FloatDelegateWithDefault(
-        private val key: String,
-        private val default: Float,
+    private val key: String,
+    private val default: Float,
 ) : ReadWriteProperty<Krate, Float> {
 
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): Float {
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/default/IntDelegateWithDefault.kt b/krate/src/main/kotlin/hu/autsoft/krate/default/IntDelegateWithDefault.kt
index f75d21a..2eea0d7 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/default/IntDelegateWithDefault.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/default/IntDelegateWithDefault.kt
@@ -6,8 +6,8 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class IntDelegateWithDefault(
-        private val key: String,
-        private val default: Int,
+    private val key: String,
+    private val default: Int,
 ) : ReadWriteProperty<Krate, Int> {
 
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int {
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/default/LongDelegateWithDefault.kt b/krate/src/main/kotlin/hu/autsoft/krate/default/LongDelegateWithDefault.kt
index 4763965..3ec5562 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/default/LongDelegateWithDefault.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/default/LongDelegateWithDefault.kt
@@ -6,8 +6,8 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class LongDelegateWithDefault(
-        private val key: String,
-        private val default: Long,
+    private val key: String,
+    private val default: Long,
 ) : ReadWriteProperty<Krate, Long> {
 
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): Long {
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/default/StringDelegateWithDefault.kt b/krate/src/main/kotlin/hu/autsoft/krate/default/StringDelegateWithDefault.kt
index fb686c0..721fa1c 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/default/StringDelegateWithDefault.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/default/StringDelegateWithDefault.kt
@@ -6,8 +6,8 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class StringDelegateWithDefault(
-        private val key: String,
-        private val default: String,
+    private val key: String,
+    private val default: String,
 ) : ReadWriteProperty<Krate, String> {
 
     @Suppress("NULLABILITY_MISMATCH_BASED_ON_JAVA_ANNOTATIONS")
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/default/StringSetDelegateWithDefault.kt b/krate/src/main/kotlin/hu/autsoft/krate/default/StringSetDelegateWithDefault.kt
index 00d9d0a..3bd5a96 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/default/StringSetDelegateWithDefault.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/default/StringSetDelegateWithDefault.kt
@@ -6,8 +6,8 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class StringSetDelegateWithDefault(
-        private val key: String,
-        private val default: Set<String>,
+    private val key: String,
+    private val default: Set<String>,
 ) : ReadWriteProperty<Krate, Set<String>> {
 
     @Suppress("NULLABILITY_MISMATCH_BASED_ON_JAVA_ANNOTATIONS")
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/internal/InternalKrateApi.kt b/krate/src/main/kotlin/hu/autsoft/krate/internal/InternalKrateApi.kt
index 213fa5d..2601bbb 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/internal/InternalKrateApi.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/internal/InternalKrateApi.kt
@@ -1,8 +1,8 @@
 package hu.autsoft.krate.internal
 
 @RequiresOptIn(
-        message = "This API is meant to be used by Krate's own modules, and third-party extensions to Krate. " +
-                "If you're a client of the Krate library, you probably shouldn't be using it.",
-        level = RequiresOptIn.Level.ERROR
+    message = "This API is meant to be used by Krate's own modules, and third-party extensions to Krate. " +
+            "If you're a client of the Krate library, you probably shouldn't be using it.",
+    level = RequiresOptIn.Level.ERROR
 )
 public annotation class InternalKrateApi
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/optional/BooleanDelegate.kt b/krate/src/main/kotlin/hu/autsoft/krate/optional/BooleanDelegate.kt
index 5e559f9..0e54d1c 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/optional/BooleanDelegate.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/optional/BooleanDelegate.kt
@@ -6,7 +6,7 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class BooleanDelegate(
-        private val key: String,
+    private val key: String,
 ) : ReadWriteProperty<Krate, Boolean?> {
 
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): Boolean? {
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/optional/FloatDelegate.kt b/krate/src/main/kotlin/hu/autsoft/krate/optional/FloatDelegate.kt
index e7414f8..3d1285c 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/optional/FloatDelegate.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/optional/FloatDelegate.kt
@@ -6,7 +6,7 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class FloatDelegate(
-        private val key: String,
+    private val key: String,
 ) : ReadWriteProperty<Krate, Float?> {
 
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): Float? {
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/optional/IntDelegate.kt b/krate/src/main/kotlin/hu/autsoft/krate/optional/IntDelegate.kt
index 2249794..7797cdb 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/optional/IntDelegate.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/optional/IntDelegate.kt
@@ -6,7 +6,7 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class IntDelegate(
-        private val key: String,
+    private val key: String,
 ) : ReadWriteProperty<Krate, Int?> {
 
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int? {
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/optional/LongDelegate.kt b/krate/src/main/kotlin/hu/autsoft/krate/optional/LongDelegate.kt
index 3ba63ea..fab65f3 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/optional/LongDelegate.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/optional/LongDelegate.kt
@@ -6,7 +6,7 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class LongDelegate(
-        private val key: String,
+    private val key: String,
 ) : ReadWriteProperty<Krate, Long?> {
 
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): Long? {
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/optional/StringDelegate.kt b/krate/src/main/kotlin/hu/autsoft/krate/optional/StringDelegate.kt
index d382c92..46fce62 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/optional/StringDelegate.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/optional/StringDelegate.kt
@@ -6,7 +6,7 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class StringDelegate(
-        private val key: String,
+    private val key: String,
 ) : ReadWriteProperty<Krate, String?> {
 
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): String? {
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/optional/StringSetDelegate.kt b/krate/src/main/kotlin/hu/autsoft/krate/optional/StringSetDelegate.kt
index 272bce6..2f58ab5 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/optional/StringSetDelegate.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/optional/StringSetDelegate.kt
@@ -6,7 +6,7 @@ import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
 internal class StringSetDelegate(
-        private val key: String,
+    private val key: String,
 ) : ReadWriteProperty<Krate, Set<String>?> {
 
     override operator fun getValue(thisRef: Krate, property: KProperty<*>): Set<String>? {
diff --git a/krate/src/main/kotlin/hu/autsoft/krate/validation/ValidatedPreferenceDelegate.kt b/krate/src/main/kotlin/hu/autsoft/krate/validation/ValidatedPreferenceDelegate.kt
index 3a7a0dd..0f40cf8 100644
--- a/krate/src/main/kotlin/hu/autsoft/krate/validation/ValidatedPreferenceDelegate.kt
+++ b/krate/src/main/kotlin/hu/autsoft/krate/validation/ValidatedPreferenceDelegate.kt
@@ -2,6 +2,7 @@ package hu.autsoft.krate.validation
 
 import hu.autsoft.krate.Krate
 import hu.autsoft.krate.internal.InternalKrateApi
+import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
@@ -14,8 +15,8 @@ import kotlin.reflect.KProperty
  */
 @InternalKrateApi
 public class ValidatedPreferenceDelegate<T>(
-        private val delegate: ReadWriteProperty<Krate, T>,
-        private val isValid: (newValue: T) -> Boolean,
+    private val delegate: ReadWriteProperty<Krate, T>,
+    private val isValid: (newValue: T) -> Boolean,
 ) : ReadWriteProperty<Krate, T> by delegate {
 
     override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T) {
@@ -26,6 +27,20 @@ public class ValidatedPreferenceDelegate<T>(
 
 }
 
+@InternalKrateApi
+public class ValidatedPreferenceDelegateFactory<T>(
+    private val propertyDelegateProvider: PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>>,
+    private val isValid: (newValue: T) -> Boolean,
+) : PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
+
+    override fun provideDelegate(thisRef: Krate, property: KProperty<*>): ReadWriteProperty<Krate, T> {
+        return ValidatedPreferenceDelegate(
+            delegate = propertyDelegateProvider.provideDelegate(thisRef, property),
+            isValid = isValid,
+        )
+    }
+}
+
 /**
  * Adds validation to a Krate delegate.
  *
@@ -42,8 +57,30 @@ public class ValidatedPreferenceDelegate<T>(
  * ```
  */
 public fun <T : Any?> ReadWriteProperty<Krate, T>.validate(
-        isValid: (newValue: T) -> Boolean,
+    isValid: (newValue: T) -> Boolean,
 ): ReadWriteProperty<Krate, T> {
     @OptIn(InternalKrateApi::class)
     return ValidatedPreferenceDelegate(this, isValid)
 }
+
+/**
+ * Adds validation to a Krate delegate factory.
+ *
+ * If a value being set to this preference returns `false` when checked by [isValid],
+ * an [IllegalArgumentException] will be thrown.
+ *
+ * Example property using this function for validation:
+ *
+ * ```kotlin
+ * var validatedModel by kotlinxPref("validatedModel")
+ *      .validate { newValue ->
+ *          newValue.x > 3 // arbitrary condition
+ *      }
+ * ```
+ */
+public fun <T : Any?> PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>>.validate(
+    isValid: (newValue: T) -> Boolean,
+): PropertyDelegateProvider<Krate, ReadWriteProperty<Krate, T>> {
+    @OptIn(InternalKrateApi::class)
+    return ValidatedPreferenceDelegateFactory(this, isValid)
+}
diff --git a/krate/src/test/java/hu/autsoft/krate/TestKrate.kt b/krate/src/test/java/hu/autsoft/krate/TestKrate.kt
index c138410..f9a11fc 100644
--- a/krate/src/test/java/hu/autsoft/krate/TestKrate.kt
+++ b/krate/src/test/java/hu/autsoft/krate/TestKrate.kt
@@ -16,8 +16,8 @@ internal class TestKrate(context: Context) : SimpleKrate(context) {
     var optionalString by stringPref("optionalString")
     var optionalStringSet by stringSetPref("optionalStringSet")
     var optionalValidatedString by stringPref("optionalValidatedString")
-            .validate { it?.length ?: 5 == 5 }
+        .validate { it?.length ?: 5 == 5 }
     var defaultValidatedFloat by floatPref("defaultValidatedFloat", 0.0f)
-            .validate { it in 0.0f..1.0f }
+        .validate { it in 0.0f..1.0f }
 
 }