diff --git a/docs/src/content/docs/internals/adding-and-overriding-definitions.mdx b/docs/src/content/docs/internals/adding-and-overriding-definitions.mdx
index e46d21d..809953a 100644
--- a/docs/src/content/docs/internals/adding-and-overriding-definitions.mdx
+++ b/docs/src/content/docs/internals/adding-and-overriding-definitions.mdx
@@ -83,6 +83,6 @@ you can effectively override the definition of any type (including PHP internal
 use GoodPhp\Reflection\ReflectorBuilder;
 
 $reflector = new ReflectorBuilder()
-	->withAddedDefinitionProvider(new YourCustomDefinitionProvider(), prepend: true)
+	->withAddedFallbackDefinitionProvider(new YourCustomDefinitionProvider())
 	->build();
 ```
diff --git a/src/NativePHPDoc/Definition/Fallback/FallbackDefinitionProvider.php b/src/NativePHPDoc/Definition/FallbackDefinitionProvider.php
similarity index 79%
rename from src/NativePHPDoc/Definition/Fallback/FallbackDefinitionProvider.php
rename to src/NativePHPDoc/Definition/FallbackDefinitionProvider.php
index 56053ca..3828bbe 100644
--- a/src/NativePHPDoc/Definition/Fallback/FallbackDefinitionProvider.php
+++ b/src/NativePHPDoc/Definition/FallbackDefinitionProvider.php
@@ -1,9 +1,6 @@
 <?php
 
-namespace GoodPhp\Reflection\NativePHPDoc\Definition\Fallback;
-
-use GoodPhp\Reflection\NativePHPDoc\Definition\DefinitionProvider;
-use GoodPhp\Reflection\NativePHPDoc\Definition\TypeDefinition;
+namespace GoodPhp\Reflection\NativePHPDoc\Definition;
 
 class FallbackDefinitionProvider implements DefinitionProvider
 {
diff --git a/src/NativePHPDoc/Definition/LazyDefinitionProvider.php b/src/NativePHPDoc/Definition/LazyDefinitionProvider.php
new file mode 100644
index 0000000..2a9055f
--- /dev/null
+++ b/src/NativePHPDoc/Definition/LazyDefinitionProvider.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace GoodPhp\Reflection\NativePHPDoc\Definition;
+
+class LazyDefinitionProvider implements DefinitionProvider
+{
+	private readonly DefinitionProvider $provider;
+
+	/**
+	 * @param callable(): DefinitionProvider $resolve
+	 */
+	public function __construct(
+		private readonly mixed $resolve,
+	) {}
+
+	public function forType(string $type): ?TypeDefinition
+	{
+		return $this->provider()->forType($type);
+	}
+
+	private function provider(): DefinitionProvider
+	{
+		return $this->provider ??= ($this->resolve)();
+	}
+}
diff --git a/src/ReflectorBuilder.php b/src/ReflectorBuilder.php
index 0b9a804..19076e9 100644
--- a/src/ReflectorBuilder.php
+++ b/src/ReflectorBuilder.php
@@ -11,7 +11,8 @@
 use GoodPhp\Reflection\NativePHPDoc\Definition\Cache\FileModificationCacheDefinitionProvider;
 use GoodPhp\Reflection\NativePHPDoc\Definition\Cache\StaticCacheDefinitionProvider;
 use GoodPhp\Reflection\NativePHPDoc\Definition\DefinitionProvider;
-use GoodPhp\Reflection\NativePHPDoc\Definition\Fallback\FallbackDefinitionProvider;
+use GoodPhp\Reflection\NativePHPDoc\Definition\FallbackDefinitionProvider;
+use GoodPhp\Reflection\NativePHPDoc\Definition\LazyDefinitionProvider;
 use GoodPhp\Reflection\NativePHPDoc\Definition\NativePHPDoc\File\FileContextParser;
 use GoodPhp\Reflection\NativePHPDoc\Definition\NativePHPDoc\Native\NativeTypeMapper;
 use GoodPhp\Reflection\NativePHPDoc\Definition\NativePHPDoc\NativePHPDocDefinitionProvider;
@@ -33,30 +34,47 @@
 
 class ReflectorBuilder
 {
+	/** @var list<DefinitionProvider> */
+	private array $addedFallbackDefinitionProviders = [];
+
 	private ?DefinitionProvider $innerDefinitionProvider = null;
 
+	/** @var callable(DefinitionProvider): DefinitionProvider|null */
+	private mixed $wrapInnerDefinitionProvider = null;
+
 	private ?DefinitionProvider $definitionProvider = null;
 
+	/** @var callable(DefinitionProvider): DefinitionProvider|null */
+	private mixed $wrapDefinitionProvider = null;
+
 	private (CacheItemPoolInterface&NamespacedPoolInterface)|null $inMemoryCache = null;
 
+	/**
+	 * Use file cache to cache definitions of the inner provider. Can (and should) be used together with {@see withMemoryCache()}
+	 */
 	public function withFileCache(?string $path = null, ?DateInterval $ttl = null): self
 	{
 		$path ??= sys_get_temp_dir() . '/good-php-reflection';
 
-		return $this->withInnerDefinitionProvider(new FileModificationCacheDefinitionProvider(
-			$this->innerDefinitionProvider(),
-			new VerifiedCache(
-				new Psr16Cache(
-					new PhpFilesAdapter(
-						namespace: (string) InstalledVersions::getReference('good-php/reflection'),
-						defaultLifetime: (int) $ttl?->format('s'),
-						directory: $path,
+		return $this->wrapInnerDefinitionProvider(
+			fn (DefinitionProvider $provider) => new FileModificationCacheDefinitionProvider(
+				$provider,
+				new VerifiedCache(
+					new Psr16Cache(
+						new PhpFilesAdapter(
+							namespace: (string) InstalledVersions::getReference('good-php/reflection'),
+							defaultLifetime: (int) $ttl?->format('s'),
+							directory: $path,
+						)
 					)
 				)
 			)
-		));
+		);
 	}
 
+	/**
+	 * Use memory cache to cache all definitions. Can (and should) be used together with {@see withFileCache()}
+	 */
 	public function withMemoryCache(int $maxItems = 100, ?DateInterval $ttl = null): self
 	{
 		$this->inMemoryCache = new ArrayAdapter(
@@ -65,24 +83,20 @@ public function withMemoryCache(int $maxItems = 100, ?DateInterval $ttl = null):
 			maxItems: $maxItems,
 		);
 
-		return $this->withDefinitionProvider(new StaticCacheDefinitionProvider(
-			$this->definitionProvider(),
-			new Psr16Cache($this->inMemoryCache->withSubNamespace('definitions'))
-		));
+		return $this->wrapDefinitionProvider(
+			fn (DefinitionProvider $provider) => new StaticCacheDefinitionProvider(
+				$provider,
+				new Psr16Cache($this->inMemoryCache->withSubNamespace('definitions'))
+			)
+		);
 	}
 
-	public function build(): Reflector
+	public function withAddedFallbackDefinitionProvider(DefinitionProvider $provider): self
 	{
-		$reflector = new DefinitionProviderReflector($this->definitionProvider());
-
-		if ($this->inMemoryCache) {
-			$reflector = new StaticCacheReflector(
-				$reflector,
-				new Psr16Cache($this->inMemoryCache->withSubNamespace('reflections'))
-			);
-		}
+		$builder = clone $this;
+		$builder->addedFallbackDefinitionProviders[] = $provider;
 
-		return $reflector;
+		return $builder;
 	}
 
 	public function withInnerDefinitionProvider(DefinitionProvider $provider): self
@@ -93,6 +107,17 @@ public function withInnerDefinitionProvider(DefinitionProvider $provider): self
 		return $builder;
 	}
 
+	/**
+	 * @param callable(DefinitionProvider): DefinitionProvider $wrap
+	 */
+	public function wrapInnerDefinitionProvider(callable $wrap): self
+	{
+		$builder = clone $this;
+		$builder->wrapInnerDefinitionProvider = $wrap;
+
+		return $builder;
+	}
+
 	public function withDefinitionProvider(DefinitionProvider $provider): self
 	{
 		$builder = clone $this;
@@ -101,37 +126,75 @@ public function withDefinitionProvider(DefinitionProvider $provider): self
 		return $builder;
 	}
 
-	public function innerDefinitionProvider(): DefinitionProvider
+	/**
+	 * @param callable(DefinitionProvider): DefinitionProvider $wrap
+	 */
+	public function wrapDefinitionProvider(callable $wrap): self
 	{
-		if ($this->innerDefinitionProvider) {
-			return $this->innerDefinitionProvider;
+		$builder = clone $this;
+		$builder->wrapDefinitionProvider = $wrap;
+
+		return $builder;
+	}
+
+	public function build(): Reflector
+	{
+		$reflector = new DefinitionProviderReflector($this->definitionProvider());
+
+		if ($this->inMemoryCache) {
+			$reflector = new StaticCacheReflector(
+				$reflector,
+				new Psr16Cache($this->inMemoryCache->withSubNamespace('reflections'))
+			);
 		}
 
-		$config = new ParserConfig(usedAttributes: []);
-		$typeAliasResolver = new TypeAliasResolver();
-		$constExprParser = new ConstExprParser($config);
-		$typeParser = new TypeParser($config, $constExprParser);
-		$phpDocParser = new PhpDocParser($config, $typeParser, $constExprParser);
-		$lexer = new Lexer($config);
-		$phpDocStringParser = new PhpDocStringParser($lexer, $phpDocParser);
-
-		return $this->innerDefinitionProvider = new NativePHPDocDefinitionProvider(
-			$phpDocStringParser,
-			new FileContextParser(
-				(new ParserFactory())->createForNewestSupportedVersion(),
-			),
-			$typeAliasResolver,
-			new NativeTypeMapper(),
-			new PhpDocTypeMapper($typeAliasResolver),
-		);
+		return $reflector;
+	}
+
+	private function innerDefinitionProvider(): DefinitionProvider
+	{
+		// Resolving some of these dependencies is quite expensive. So if we can
+		// avoid doing so with fully cached definitions, then we should do so :)
+		$provider = $this->innerDefinitionProvider ?? new LazyDefinitionProvider(static function () {
+			$config = new ParserConfig(usedAttributes: []);
+			$typeAliasResolver = new TypeAliasResolver();
+			$constExprParser = new ConstExprParser($config);
+			$typeParser = new TypeParser($config, $constExprParser);
+			$phpDocParser = new PhpDocParser($config, $typeParser, $constExprParser);
+			$lexer = new Lexer($config);
+			$phpDocStringParser = new PhpDocStringParser($lexer, $phpDocParser);
+
+			return new NativePHPDocDefinitionProvider(
+				$phpDocStringParser,
+				new FileContextParser(
+					(new ParserFactory())->createForNewestSupportedVersion(),
+				),
+				$typeAliasResolver,
+				new NativeTypeMapper(),
+				new PhpDocTypeMapper($typeAliasResolver),
+			);
+		});
+
+		return $this->wrapInnerDefinitionProvider ? ($this->wrapInnerDefinitionProvider)($provider) : $provider;
+	}
+
+	private function definitionProvider(): DefinitionProvider
+	{
+		$provider = $this->definitionProvider ?? new FallbackDefinitionProvider($this->fallbackDefinitionProviders());
+
+		return $this->wrapDefinitionProvider ? ($this->wrapDefinitionProvider)($provider) : $provider;
 	}
 
-	public function definitionProvider(): DefinitionProvider
+	/**
+	 * @return list<DefinitionProvider>
+	 */
+	private function fallbackDefinitionProviders(): array
 	{
-		return $this->definitionProvider ??= new FallbackDefinitionProvider([
+		return [
+			...$this->addedFallbackDefinitionProviders,
 			new BuiltInSpecialsDefinitionProvider(),
 			new BuiltInCoreDefinitionProvider(),
 			$this->innerDefinitionProvider(),
-		]);
+		];
 	}
 }
diff --git a/tests/Unit/Reflection/ReflectorBuilderTest.php b/tests/Unit/Reflection/ReflectorBuilderTest.php
new file mode 100644
index 0000000..94e5728
--- /dev/null
+++ b/tests/Unit/Reflection/ReflectorBuilderTest.php
@@ -0,0 +1,37 @@
+<?php
+
+namespace Tests\Unit\Reflection;
+
+use GoodPhp\Reflection\NativePHPDoc\Definition\DefinitionProvider;
+use GoodPhp\Reflection\NativePHPDoc\Definition\TypeDefinition;
+use GoodPhp\Reflection\Reflection\SpecialTypeReflection;
+use GoodPhp\Reflection\ReflectorBuilder;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\TestCase;
+use RuntimeException;
+
+#[CoversClass(ReflectorBuilder::class)]
+class ReflectorBuilderTest extends TestCase
+{
+	public function testBuildsWithAddedReflectionProvider(): void
+	{
+		$reflector = (new ReflectorBuilder())
+			->withMemoryCache()
+			->withAddedFallbackDefinitionProvider(new class () implements DefinitionProvider {
+				public function forType(string $type): ?TypeDefinition
+				{
+					if ($type === 'test') {
+						throw new RuntimeException('My provider');
+					}
+
+					return null;
+				}
+			})
+			->build();
+
+		self::assertInstanceOf(SpecialTypeReflection::class, $reflector->forType('string'));
+
+		$this->expectExceptionObject(new RuntimeException('My provider'));
+		$reflector->forType('test');
+	}
+}