diff --git a/mek_data_class_generator/CHANGELOG.md b/mek_data_class_generator/CHANGELOG.md
index 950e816..27fcaf9 100644
--- a/mek_data_class_generator/CHANGELOG.md
+++ b/mek_data_class_generator/CHANGELOG.md
@@ -1,3 +1,5 @@
+## 1.3.1
+- fix: private fields class generation
 
 ## 1.3.0
 - fix: unnecessary parentheses on `toString` method [#20](https://github.com/BreX900/data_class/issues/20)
diff --git a/mek_data_class_generator/lib/src/creators/fields_class_creator.dart b/mek_data_class_generator/lib/src/creators/fields_class_creator.dart
index fe35bca..7bedb93 100644
--- a/mek_data_class_generator/lib/src/creators/fields_class_creator.dart
+++ b/mek_data_class_generator/lib/src/creators/fields_class_creator.dart
@@ -28,6 +28,8 @@ class FieldsClassCreator extends Creator {
     yield createLibraryClassFields();
   }
 
+  String get _classPrefix => config.fieldsClassVisible ? '' : '_';
+
   String _createFieldPath(FieldSpec fieldSpec, bool hasFieldMap) {
     return hasFieldMap ? '\$_path\${_get(\'${fieldSpec.name}\')}' : '\${_path}${fieldSpec.name}';
   }
@@ -42,7 +44,7 @@ class FieldsClassCreator extends Creator {
     final fieldClassSpec = ClassSpec.from(config, fieldClassElement, fieldClassReader);
     if (!fieldClassSpec.createFieldsClass) return null;
 
-    final keysClassName = '${fieldClassElement.name}Fields';
+    final keysClassName = '$_classPrefix${fieldClassElement.name}Fields';
 
     return Method((b) => b
       ..returns = Reference(keysClassName)
@@ -56,7 +58,7 @@ class FieldsClassCreator extends Creator {
     final jsonSerializable = _jsonSerializableType.firstAnnotationOf(classSpec.element);
     final hasFieldMap = ConstantReader(jsonSerializable).peek('createFieldMap')?.boolValue ?? false;
 
-    final className = '${config.fieldsClassVisible ? '' : '_'}${classSpec.element.name}Fields';
+    final className = '$_classPrefix${classSpec.element.name}Fields';
 
     final methodsFields = _paramsSpecs.map((field) {
       final fieldPath = _createFieldPath(field, hasFieldMap);
diff --git a/mek_data_class_generator/pubspec.yaml b/mek_data_class_generator/pubspec.yaml
index 6658d52..de9da0e 100644
--- a/mek_data_class_generator/pubspec.yaml
+++ b/mek_data_class_generator/pubspec.yaml
@@ -1,5 +1,5 @@
 name: mek_data_class_generator
-version: 1.3.0
+version: 1.3.1
 description: >
   Code generator for data_class to generate `hashCode`, `==`, `toString`, `copyWith` 
   and `change` methods