diff --git a/.rubocop.yml b/.rubocop.yml
index c179d785..28a4b0b6 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -8,6 +8,8 @@ Metrics/BlockLength:
   Exclude:
   - 'spec/**/*.rb'
   - '*.gemspec'
+Metrics/MethodLength:
+  Max: 20
 Layout/EmptyLinesAroundAttributeAccessor:
   Enabled: true
 Layout/SpaceAroundMethodCallOperator:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3a4f02bc..02c73ac0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # Changelog
 
 ## Unreleased
+- Support nullable: true
 - Request validation fails if request includes a property with `readOnly: true`
 - Response validation fails if response body includes a property with `writeOnly: true`
 
diff --git a/lib/openapi_first/operation.rb b/lib/openapi_first/operation.rb
index d5fb423e..12505b61 100644
--- a/lib/openapi_first/operation.rb
+++ b/lib/openapi_first/operation.rb
@@ -99,7 +99,7 @@ def build_parameters_json_schema
       end
     end
 
-    def generate_schema(schema, params, parameter) # rubocop:disable Metrics/MethodLength
+    def generate_schema(schema, params, parameter)
       required = Set.new(schema['required'])
       params.each do |key, value|
         required << key if parameter.required
diff --git a/lib/openapi_first/request_validation.rb b/lib/openapi_first/request_validation.rb
index af534d49..c0d8023a 100644
--- a/lib/openapi_first/request_validation.rb
+++ b/lib/openapi_first/request_validation.rb
@@ -16,7 +16,7 @@ def initialize(app, raise_error: false)
       @raise = raise_error
     end
 
-    def call(env) # rubocop:disable Metrics/AbcSize, Metrics/MethodLength
+    def call(env) # rubocop:disable Metrics/AbcSize
       operation = env[OpenapiFirst::OPERATION]
       return @app.call(env) unless operation
 
diff --git a/lib/openapi_first/router.rb b/lib/openapi_first/router.rb
index c33a578b..07c07848 100644
--- a/lib/openapi_first/router.rb
+++ b/lib/openapi_first/router.rb
@@ -53,7 +53,7 @@ def call_router(env)
       env[Rack::PATH_INFO] = env.delete(ORIGINAL_PATH) if env[ORIGINAL_PATH]
     end
 
-    def build_router(operations) # rubocop:disable Metrics/AbcSize, Metrics/MethodLength
+    def build_router(operations) # rubocop:disable Metrics/AbcSize
       router = Hanami::Router.new {}
       operations.each do |operation|
         normalized_path = operation.path.gsub('{', ':').gsub('}', '')
diff --git a/lib/openapi_first/schema_validation.rb b/lib/openapi_first/schema_validation.rb
index e0d5d08d..c0851256 100644
--- a/lib/openapi_first/schema_validation.rb
+++ b/lib/openapi_first/schema_validation.rb
@@ -3,7 +3,6 @@
 require 'json_schemer'
 
 module OpenapiFirst
-  # Wraps JSONSchemer, mostly to add raw_schema method to test things :|
   class SchemaValidation
     attr_reader :raw_schema
 
@@ -14,12 +13,24 @@ def initialize(schema, write: true)
       custom_keywords['readOnly'] = proc { |data| !data } if write
       @schemer = JSONSchemer.schema(
         schema,
-        keywords: custom_keywords
+        keywords: custom_keywords,
+        before_property_validation: proc do |data, property, property_schema, parent|
+          convert_nullable(data, property, property_schema, parent)
+        end
       )
     end
 
     def validate(input)
       @schemer.validate(input)
     end
+
+    private
+
+    def convert_nullable(_data, _property, property_schema, _parent)
+      return unless property_schema.is_a?(Hash) && property_schema['nullable'] && property_schema['type']
+
+      property_schema['type'] = [*property_schema['type'], 'null']
+      property_schema.delete('nullable')
+    end
   end
 end
diff --git a/spec/data/nullable.yaml b/spec/data/nullable.yaml
new file mode 100644
index 00000000..03681e78
--- /dev/null
+++ b/spec/data/nullable.yaml
@@ -0,0 +1,35 @@
+openapi: '3.0.2'
+paths:
+  /test:
+    post:
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/Test'
+      responses:
+        '201':
+          description: Created
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Test'
+    get:
+      responses:
+        '200':
+          description: Ok
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Test'
+components:
+  schemas:
+    Test:
+      type: object
+      required:
+        - name
+      properties:
+        name:
+          type: string
+          nullable: true
+
diff --git a/spec/request_validation/request_body_validation_spec.rb b/spec/request_validation/request_body_validation_spec.rb
index 7f2c6965..0253e171 100644
--- a/spec/request_validation/request_body_validation_spec.rb
+++ b/spec/request_validation/request_body_validation_spec.rb
@@ -198,6 +198,35 @@
       end
     end
 
+    describe 'with a required nullable field' do
+      let(:app) do
+        Rack::Builder.new do
+          spec = OpenapiFirst.load('./spec/data/nullable.yaml')
+          use OpenapiFirst::Router, spec: spec, raise_error: true
+          use OpenapiFirst::RequestValidation, raise_error: true
+          run lambda { |_env|
+            Rack::Response.new('hello', 201).finish
+          }
+        end
+      end
+
+      it 'fails if field is missing' do
+        header Rack::CONTENT_TYPE, 'application/json'
+        expect do
+          post '/test', json_dump({})
+        end.to raise_error OpenapiFirst::RequestInvalidError, 'Request body invalid: is missing required properties: name' # rubocop:disable Layout/LineLength
+      end
+
+      it 'succeeds if field is nil' do
+        header Rack::CONTENT_TYPE, 'application/json'
+        request_body = {
+          name: nil
+        }
+        post '/test', json_dump(request_body)
+        expect(last_response.status).to eq 201
+      end
+    end
+
     describe 'raise_error: true' do
       let(:raise_error_option) { true }
 
diff --git a/spec/response_validation_spec.rb b/spec/response_validation_spec.rb
index 343c04fc..2ffd37bc 100644
--- a/spec/response_validation_spec.rb
+++ b/spec/response_validation_spec.rb
@@ -194,6 +194,31 @@
     end
   end
 
-  describe 'unknown content-type' do
+  describe 'with a required nullable field' do
+    let(:spec) { OpenapiFirst.load('./spec/data/nullable.yaml') }
+
+    describe 'when the field is missing' do
+      let(:response_body) do
+        json_dump({})
+      end
+
+      it 'raises an error' do
+        message = 'is missing required properties: name '
+        expect do
+          get '/test'
+        end.to raise_error OpenapiFirst::ResponseBodyInvalidError, message
+      end
+    end
+
+    describe 'when the field is nil' do
+      let(:response_body) do
+        json_dump({ name: nil })
+      end
+
+      it 'does not raise an error' do
+        get '/test'
+        expect(last_response.status).to eq 200
+      end
+    end
   end
 end