diff --git a/example/lib/example.dart b/example/lib/example.dart
index 0cd0e650f..2605e603f 100644
--- a/example/lib/example.dart
+++ b/example/lib/example.dart
@@ -25,10 +25,6 @@ class Person {
   Person(this.firstName, this.lastName, this.dateOfBirth,
       {this.middleName, this.lastOrder, List<Order> orders})
       : orders = orders ?? <Order>[];
-
-  factory Person.fromJson(Map<String, dynamic> json) => _$PersonFromJson(json);
-
-  Map<String, dynamic> toJson() => _$PersonToJson(this);
 }
 
 @JsonSerializable(includeIfNull: false)
@@ -49,10 +45,6 @@ class Order {
 
   Order(this.date);
 
-  factory Order.fromJson(Map<String, dynamic> json) => _$OrderFromJson(json);
-
-  Map<String, dynamic> toJson() => _$OrderToJson(this);
-
   static Duration _durationFromMilliseconds(int milliseconds) =>
       milliseconds == null ? null : Duration(milliseconds: milliseconds);
 
@@ -73,10 +65,6 @@ class Item {
   bool isRushed;
 
   Item();
-
-  factory Item.fromJson(Map<String, dynamic> json) => _$ItemFromJson(json);
-
-  Map<String, dynamic> toJson() => _$ItemToJson(this);
 }
 
 @JsonLiteral('data.json')
diff --git a/example/lib/example.g.dart b/example/lib/example.g.dart
index 44599902e..2565e6eac 100644
--- a/example/lib/example.g.dart
+++ b/example/lib/example.g.dart
@@ -6,6 +6,11 @@ part of 'example.dart';
 // JsonSerializableGenerator
 // **************************************************************************
 
+extension PersonExt on Person {
+  static Person fromJson(Map<String, dynamic> json) => _$PersonFromJson(json);
+  Map<String, dynamic> toJson() => _$PersonToJson(this);
+}
+
 Person _$PersonFromJson(Map<String, dynamic> json) {
   return Person(
     json['firstName'] as String,
@@ -16,7 +21,7 @@ Person _$PersonFromJson(Map<String, dynamic> json) {
         ? null
         : DateTime.parse(json['last-order'] as String),
     orders: (json['orders'] as List)
-        .map((e) => Order.fromJson(e as Map<String, dynamic>))
+        .map((e) => OrderExt.fromJson(e as Map<String, dynamic>))
         .toList(),
   );
 }
@@ -40,6 +45,11 @@ Map<String, dynamic> _$PersonToJson(Person instance) {
   return val;
 }
 
+extension OrderExt on Order {
+  static Order fromJson(Map<String, dynamic> json) => _$OrderFromJson(json);
+  Map<String, dynamic> toJson() => _$OrderToJson(this);
+}
+
 Order _$OrderFromJson(Map<String, dynamic> json) {
   return Order(
     Order._dateTimeFromEpochUs(json['date'] as int),
@@ -49,7 +59,7 @@ Order _$OrderFromJson(Map<String, dynamic> json) {
     ..isRushed = json['isRushed'] as bool
     ..item = json['item'] == null
         ? null
-        : Item.fromJson(json['item'] as Map<String, dynamic>)
+        : ItemExt.fromJson(json['item'] as Map<String, dynamic>)
     ..prepTime = Order._durationFromMilliseconds(json['prep-time'] as int);
 }
 
@@ -71,6 +81,11 @@ Map<String, dynamic> _$OrderToJson(Order instance) {
   return val;
 }
 
+extension ItemExt on Item {
+  static Item fromJson(Map<String, dynamic> json) => _$ItemFromJson(json);
+  Map<String, dynamic> toJson() => _$ItemToJson(this);
+}
+
 Item _$ItemFromJson(Map<String, dynamic> json) {
   return Item()
     ..count = json['count'] as int
diff --git a/example/lib/json_converter_example.g.dart b/example/lib/json_converter_example.g.dart
index 709e2e79b..acaf10163 100644
--- a/example/lib/json_converter_example.g.dart
+++ b/example/lib/json_converter_example.g.dart
@@ -6,6 +6,12 @@ part of 'json_converter_example.dart';
 // JsonSerializableGenerator
 // **************************************************************************
 
+extension GenericCollectionExt on GenericCollection {
+  static GenericCollection fromJson(Map<String, dynamic> json) =>
+      _$GenericCollectionFromJson(json);
+  Map<String, dynamic> toJson() => _$GenericCollectionToJson(this);
+}
+
 GenericCollection<T> _$GenericCollectionFromJson<T>(Map<String, dynamic> json) {
   return GenericCollection<T>(
     page: json['page'] as int,
@@ -24,6 +30,12 @@ Map<String, dynamic> _$GenericCollectionToJson<T>(
       'results': instance.results?.map(_Converter<T>().toJson)?.toList(),
     };
 
+extension CustomResultExt on CustomResult {
+  static CustomResult fromJson(Map<String, dynamic> json) =>
+      _$CustomResultFromJson(json);
+  Map<String, dynamic> toJson() => _$CustomResultToJson(this);
+}
+
 CustomResult _$CustomResultFromJson(Map<String, dynamic> json) {
   return CustomResult(
     json['name'] as String,
diff --git a/example/pubspec.yaml b/example/pubspec.yaml
index 888586fe0..77a4dba8b 100644
--- a/example/pubspec.yaml
+++ b/example/pubspec.yaml
@@ -16,5 +16,7 @@ dev_dependencies:
   test: ^1.6.0
 
 dependency_overrides:
+  json_annotation:
+    path: ../json_annotation
   json_serializable:
     path: ../json_serializable
diff --git a/example/test/example_test.dart b/example/test/example_test.dart
index 28a71c7a4..75182cd67 100644
--- a/example/test/example_test.dart
+++ b/example/test/example_test.dart
@@ -15,7 +15,7 @@ void main() {
     final personJson = _encode(person);
 
     final person2 =
-        Person.fromJson(json.decode(personJson) as Map<String, dynamic>);
+        PersonExt.fromJson(json.decode(personJson) as Map<String, dynamic>);
 
     expect(person.firstName, person2.firstName);
     expect(person.lastName, person2.lastName);
diff --git a/json_annotation/CHANGELOG.md b/json_annotation/CHANGELOG.md
index 3dedfef66..271d81c06 100644
--- a/json_annotation/CHANGELOG.md
+++ b/json_annotation/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 3.0.2
+
+- Added extension to class to remove boilerplace code
+
 ## 3.0.1
 
 - Require at least Dart `2.6.0`.
diff --git a/json_annotation/lib/src/json_serializable.dart b/json_annotation/lib/src/json_serializable.dart
index 08f74940f..681990014 100644
--- a/json_annotation/lib/src/json_serializable.dart
+++ b/json_annotation/lib/src/json_serializable.dart
@@ -47,6 +47,28 @@ class JsonSerializable {
   /// [CheckedFromJsonException] is thrown.
   final bool checked;
 
+  /// If `Ext` (the default), a named extension `ExampleExt` is created
+  /// in the generated part file.
+  ///
+  /// ```dart
+  /// extension ExampleExt on Example {
+  /// }
+  /// ```
+  final String extensionSuffix;
+
+  /// If `true` (the default), a named extension `ExampleExt` is created
+  /// in the generated part file.
+  ///
+  /// ```dart
+  /// extension ExampleExt on Example {
+  ///   Example static fromJson(Map<String, dynamic> json) =>
+  ///     _$ExampleFromJson(json);
+  ///
+  ///    Map<String, dynamic> toJson() => _$ExampleToJson(this);
+  /// }
+  /// ```
+  final bool createExtension;
+
   /// If `true` (the default), a private, static `_$ExampleFromJson` method
   /// is created in the generated part file.
   ///
@@ -143,6 +165,8 @@ class JsonSerializable {
   const JsonSerializable({
     this.anyMap,
     this.checked,
+    this.createExtension,
+    this.extensionSuffix,
     this.createFactory,
     this.createToJson,
     this.disallowUnrecognizedKeys,
@@ -161,6 +185,8 @@ class JsonSerializable {
   static const defaults = JsonSerializable(
     anyMap: false,
     checked: false,
+    createExtension: true,
+    extensionSuffix: 'Ext',
     createFactory: true,
     createToJson: true,
     disallowUnrecognizedKeys: false,
@@ -179,6 +205,8 @@ class JsonSerializable {
   JsonSerializable withDefaults() => JsonSerializable(
         anyMap: anyMap ?? defaults.anyMap,
         checked: checked ?? defaults.checked,
+        createExtension: createExtension ?? defaults.createExtension,
+        extensionSuffix: extensionSuffix ?? defaults.extensionSuffix,
         createFactory: createFactory ?? defaults.createFactory,
         createToJson: createToJson ?? defaults.createToJson,
         disallowUnrecognizedKeys:
diff --git a/json_annotation/lib/src/json_serializable.g.dart b/json_annotation/lib/src/json_serializable.g.dart
index 68cec418b..61e19db2c 100644
--- a/json_annotation/lib/src/json_serializable.g.dart
+++ b/json_annotation/lib/src/json_serializable.g.dart
@@ -12,17 +12,20 @@ JsonSerializable _$JsonSerializableFromJson(Map<String, dynamic> json) {
       'any_map',
       'checked',
       'create_factory',
+      'create_extension',
       'create_to_json',
       'disallow_unrecognized_keys',
       'explicit_to_json',
       'field_rename',
       'ignore_unannotated',
       'include_if_null',
-      'nullable',
+      'nullable'
     ]);
     final val = JsonSerializable(
       anyMap: $checkedConvert(json, 'any_map', (v) => v as bool),
       checked: $checkedConvert(json, 'checked', (v) => v as bool),
+      createExtension:
+          $checkedConvert(json, 'create_extension', (v) => v as bool),
       createFactory: $checkedConvert(json, 'create_factory', (v) => v as bool),
       createToJson: $checkedConvert(json, 'create_to_json', (v) => v as bool),
       disallowUnrecognizedKeys:
@@ -39,13 +42,14 @@ JsonSerializable _$JsonSerializableFromJson(Map<String, dynamic> json) {
     return val;
   }, fieldKeyMap: const {
     'anyMap': 'any_map',
+    'createExtension': 'create_extension',
     'createFactory': 'create_factory',
     'createToJson': 'create_to_json',
     'disallowUnrecognizedKeys': 'disallow_unrecognized_keys',
     'explicitToJson': 'explicit_to_json',
     'fieldRename': 'field_rename',
     'ignoreUnannotated': 'ignore_unannotated',
-    'includeIfNull': 'include_if_null',
+    'includeIfNull': 'include_if_null'
   });
 }
 
@@ -54,6 +58,7 @@ Map<String, dynamic> _$JsonSerializableToJson(JsonSerializable instance) =>
       'any_map': instance.anyMap,
       'checked': instance.checked,
       'create_factory': instance.createFactory,
+      'create_extension': instance.createExtension,
       'create_to_json': instance.createToJson,
       'disallow_unrecognized_keys': instance.disallowUnrecognizedKeys,
       'explicit_to_json': instance.explicitToJson,
@@ -63,29 +68,41 @@ Map<String, dynamic> _$JsonSerializableToJson(JsonSerializable instance) =>
       'nullable': instance.nullable,
     };
 
-T _$enumDecode<T>(Map<T, dynamic> enumValues, dynamic source) {
+T _$enumDecode<T>(
+  Map<T, dynamic> enumValues,
+  dynamic source, {
+  T unknownValue,
+}) {
   if (source == null) {
     throw ArgumentError('A value must be provided. Supported values: '
         '${enumValues.values.join(', ')}');
   }
-  return enumValues.entries
-      .singleWhere((e) => e.value == source,
-          orElse: () => throw ArgumentError(
-              '`$source` is not one of the supported values: '
-              '${enumValues.values.join(', ')}'))
-      .key;
+
+  final value = enumValues.entries
+      .singleWhere((e) => e.value == source, orElse: () => null)
+      ?.key;
+
+  if (value == null && unknownValue == null) {
+    throw ArgumentError('`$source` is not one of the supported values: '
+        '${enumValues.values.join(', ')}');
+  }
+  return value ?? unknownValue;
 }
 
-T _$enumDecodeNullable<T>(Map<T, dynamic> enumValues, dynamic source) {
+T _$enumDecodeNullable<T>(
+  Map<T, dynamic> enumValues,
+  dynamic source, {
+  T unknownValue,
+}) {
   if (source == null) {
     return null;
   }
-  return _$enumDecode<T>(enumValues, source);
+  return _$enumDecode<T>(enumValues, source, unknownValue: unknownValue);
 }
 
-const _$FieldRenameEnumMap = <FieldRename, dynamic>{
+const _$FieldRenameEnumMap = {
   FieldRename.none: 'none',
   FieldRename.kebab: 'kebab',
   FieldRename.snake: 'snake',
-  FieldRename.pascal: 'pascal'
+  FieldRename.pascal: 'pascal',
 };
diff --git a/json_annotation/pubspec.yaml b/json_annotation/pubspec.yaml
index 3617b673b..7baedcde4 100644
--- a/json_annotation/pubspec.yaml
+++ b/json_annotation/pubspec.yaml
@@ -1,5 +1,5 @@
 name: json_annotation
-version: 3.0.1
+version: 3.0.2
 description: >-
   Classes and helper functions that support JSON code generation via the
   `json_serializable` package.
diff --git a/json_serializable/CHANGELOG.md b/json_serializable/CHANGELOG.md
index a1142fda3..0ea84d1ec 100644
--- a/json_serializable/CHANGELOG.md
+++ b/json_serializable/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 3.4.1-dev
+
+- Generated extension code to remove boilerplate code
+
 ## 3.4.0-dev
 
 - Added support for `double` constants as default values.
diff --git a/json_serializable/doc/doc.md b/json_serializable/doc/doc.md
index 569a63d58..6594599a3 100644
--- a/json_serializable/doc/doc.md
+++ b/json_serializable/doc/doc.md
@@ -2,6 +2,7 @@
 | -------------------------- | ------------------------------------------- | --------------------------- |
 | any_map                    | [JsonSerializable.anyMap]                   |                             |
 | checked                    | [JsonSerializable.checked]                  |                             |
+| create_extension           | [JsonSerializable.createExtension]          |                             |
 | create_factory             | [JsonSerializable.createFactory]            |                             |
 | create_to_json             | [JsonSerializable.createToJson]             |                             |
 | disallow_unrecognized_keys | [JsonSerializable.disallowUnrecognizedKeys] |                             |
@@ -19,23 +20,24 @@
 |                            |                                             | [JsonKey.toJson]            |
 |                            |                                             | [JsonKey.unknownEnumValue]  |
 
-[JsonSerializable.anyMap]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonSerializable/anyMap.html
-[JsonSerializable.checked]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonSerializable/checked.html
-[JsonSerializable.createFactory]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonSerializable/createFactory.html
-[JsonSerializable.createToJson]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonSerializable/createToJson.html
-[JsonSerializable.disallowUnrecognizedKeys]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonSerializable/disallowUnrecognizedKeys.html
-[JsonSerializable.explicitToJson]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonSerializable/explicitToJson.html
-[JsonSerializable.fieldRename]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonSerializable/fieldRename.html
-[JsonSerializable.ignoreUnannotated]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonSerializable/ignoreUnannotated.html
-[JsonSerializable.includeIfNull]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonSerializable/includeIfNull.html
-[JsonKey.includeIfNull]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonKey/includeIfNull.html
-[JsonSerializable.nullable]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonSerializable/nullable.html
-[JsonKey.nullable]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonKey/nullable.html
-[JsonKey.defaultValue]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonKey/defaultValue.html
-[JsonKey.disallowNullValue]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonKey/disallowNullValue.html
-[JsonKey.fromJson]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonKey/fromJson.html
-[JsonKey.ignore]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonKey/ignore.html
-[JsonKey.name]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonKey/name.html
-[JsonKey.required]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonKey/required.html
-[JsonKey.toJson]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonKey/toJson.html
-[JsonKey.unknownEnumValue]: https://pub.dev/documentation/json_annotation/3.0.1/json_annotation/JsonKey/unknownEnumValue.html
+[JsonSerializable.anyMap]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonSerializable/anyMap.html
+[JsonSerializable.checked]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonSerializable/checked.html
+[JsonSerializable.createExtension]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonSerializable/createExtension.html
+[JsonSerializable.createFactory]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonSerializable/createFactory.html
+[JsonSerializable.createToJson]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonSerializable/createToJson.html
+[JsonSerializable.disallowUnrecognizedKeys]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonSerializable/disallowUnrecognizedKeys.html
+[JsonSerializable.explicitToJson]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonSerializable/explicitToJson.html
+[JsonSerializable.fieldRename]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonSerializable/fieldRename.html
+[JsonSerializable.ignoreUnannotated]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonSerializable/ignoreUnannotated.html
+[JsonSerializable.includeIfNull]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonSerializable/includeIfNull.html
+[JsonKey.includeIfNull]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonKey/includeIfNull.html
+[JsonSerializable.nullable]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonSerializable/nullable.html
+[JsonKey.nullable]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonKey/nullable.html
+[JsonKey.defaultValue]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonKey/defaultValue.html
+[JsonKey.disallowNullValue]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonKey/disallowNullValue.html
+[JsonKey.fromJson]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonKey/fromJson.html
+[JsonKey.ignore]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonKey/ignore.html
+[JsonKey.name]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonKey/name.html
+[JsonKey.required]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonKey/required.html
+[JsonKey.toJson]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonKey/toJson.html
+[JsonKey.unknownEnumValue]: https://pub.dev/documentation/json_annotation/3.0.2/json_annotation/JsonKey/unknownEnumValue.html
diff --git a/json_serializable/example/example.dart b/json_serializable/example/example.dart
index b62fd38f1..9197c0fb2 100644
--- a/json_serializable/example/example.dart
+++ b/json_serializable/example/example.dart
@@ -12,6 +12,4 @@ class Person {
   final String lastName;
   final DateTime dateOfBirth;
   Person({this.firstName, this.lastName, this.dateOfBirth});
-  factory Person.fromJson(Map<String, dynamic> json) => _$PersonFromJson(json);
-  Map<String, dynamic> toJson() => _$PersonToJson(this);
 }
diff --git a/json_serializable/example/example.g.dart b/json_serializable/example/example.g.dart
index 4d790cf8c..fa3ed849e 100644
--- a/json_serializable/example/example.g.dart
+++ b/json_serializable/example/example.g.dart
@@ -6,6 +6,11 @@ part of 'example.dart';
 // JsonSerializableGenerator
 // **************************************************************************
 
+extension PersonExt on Person {
+  static Person fromJson(Map<String, dynamic> json) => _$PersonFromJson(json);
+  Map<String, dynamic> toJson() => _$PersonToJson(this);
+}
+
 Person _$PersonFromJson(Map<String, dynamic> json) {
   return Person(
     firstName: json['firstName'] as String,
diff --git a/json_serializable/lib/src/extension_helper.dart b/json_serializable/lib/src/extension_helper.dart
new file mode 100644
index 000000000..f0957c1db
--- /dev/null
+++ b/json_serializable/lib/src/extension_helper.dart
@@ -0,0 +1,18 @@
+import './helper_core.dart';
+
+abstract class ExtensionHelper implements HelperCore {
+  Iterable<String> createExtension() sync* {
+    assert(config.createExtension);
+    final buffer = StringBuffer()
+      ..writeln('extension $extensionName on $className { '
+          'static $className fromJson(Map<String, dynamic> json) => ${prefix}FromJson(json); '
+          'Map<String, dynamic> toJson() => ${prefix}ToJson(this); '
+          '}');
+
+    yield buffer.toString();
+  }
+
+  String get className => element.name;
+
+  String get extensionName => '$className${config.extensionSuffix}';
+}
diff --git a/json_serializable/lib/src/json_serializable_generator.dart b/json_serializable/lib/src/json_serializable_generator.dart
index 230457e72..d74ac30b3 100644
--- a/json_serializable/lib/src/json_serializable_generator.dart
+++ b/json_serializable/lib/src/json_serializable_generator.dart
@@ -9,6 +9,7 @@ import 'package:source_gen/source_gen.dart';
 
 import 'decode_helper.dart';
 import 'encoder_helper.dart';
+import 'extension_helper.dart';
 import 'field_helpers.dart';
 import 'helper_core.dart';
 import 'type_helper.dart';
@@ -97,7 +98,8 @@ class JsonSerializableGenerator
   }
 }
 
-class _GeneratorHelper extends HelperCore with EncodeHelper, DecodeHelper {
+class _GeneratorHelper extends HelperCore
+    with EncodeHelper, DecodeHelper, ExtensionHelper {
   final JsonSerializableGenerator _generator;
   final _addedMembers = <String>{};
 
@@ -146,6 +148,10 @@ class _GeneratorHelper extends HelperCore with EncodeHelper, DecodeHelper {
       },
     );
 
+    if(config.createExtension) {
+      yield* createExtension();
+    }
+
     var accessibleFieldSet = accessibleFields.values.toSet();
     if (config.createFactory) {
       final createResult = createFactory(accessibleFields, unavailableReasons);
diff --git a/json_serializable/lib/src/type_helpers/json_helper.dart b/json_serializable/lib/src/type_helpers/json_helper.dart
index e106604f5..74c639497 100644
--- a/json_serializable/lib/src/type_helpers/json_helper.dart
+++ b/json_serializable/lib/src/type_helpers/json_helper.dart
@@ -70,7 +70,10 @@ class JsonHelper extends TypeHelper<TypeHelperContextWithConfig> {
 
     // TODO: the type could be imported from a library with a prefix!
     // https://github.com/google/json_serializable.dart/issues/19
-    output = '${targetType.element.name}.fromJson($output)';
+
+    final suffix =
+        context.config.createExtension ? context.config.extensionSuffix : '';
+    output = '${targetType.element.name}$suffix.fromJson($output)';
 
     return commonNullPrefix(context.nullable, expression, output).toString();
   }
diff --git a/json_serializable/lib/src/utils.dart b/json_serializable/lib/src/utils.dart
index 40ac04a20..f619f29f1 100644
--- a/json_serializable/lib/src/utils.dart
+++ b/json_serializable/lib/src/utils.dart
@@ -78,6 +78,8 @@ T enumValueForDartObject<T>(
 JsonSerializable _valueForAnnotation(ConstantReader reader) => JsonSerializable(
       anyMap: reader.read('anyMap').literalValue as bool,
       checked: reader.read('checked').literalValue as bool,
+      createExtension: reader.read('createExtension').literalValue as bool,
+      extensionSuffix: reader.read('extensionSuffix').literalValue as String,
       createFactory: reader.read('createFactory').literalValue as bool,
       createToJson: reader.read('createToJson').literalValue as bool,
       disallowUnrecognizedKeys:
@@ -100,6 +102,8 @@ JsonSerializable mergeConfig(JsonSerializable config, ConstantReader reader) {
   return JsonSerializable(
     anyMap: annotation.anyMap ?? config.anyMap,
     checked: annotation.checked ?? config.checked,
+    createExtension: annotation.createExtension ?? config.createExtension,
+    extensionSuffix: annotation.extensionSuffix ?? config.extensionSuffix,
     createFactory: annotation.createFactory ?? config.createFactory,
     createToJson: annotation.createToJson ?? config.createToJson,
     disallowUnrecognizedKeys:
diff --git a/json_serializable/pubspec.yaml b/json_serializable/pubspec.yaml
index 03ecfd590..b1f9127a4 100644
--- a/json_serializable/pubspec.yaml
+++ b/json_serializable/pubspec.yaml
@@ -1,5 +1,5 @@
 name: json_serializable
-version: 3.4.0-dev
+version: 3.4.1-dev
 description: >-
   Automatically generate code for converting to and from JSON by annotating
   Dart classes.
@@ -32,3 +32,7 @@ dev_dependencies:
   source_gen_test: ^0.1.0
   test: ^1.6.0
   yaml: ^2.1.13
+
+dependency_overrides:
+  json_annotation:
+    path: ../json_annotation