diff --git a/copy_with_extension/CHANGELOG.md b/copy_with_extension/CHANGELOG.md
index e0a165b..4096a13 100644
--- a/copy_with_extension/CHANGELOG.md
+++ b/copy_with_extension/CHANGELOG.md
@@ -1,3 +1,6 @@
+## 5.0.2
+* [Fix](https://github.com/numen31337/copy_with_extension/issues/79) Allow having a nullable constructor parameter with a fallback for a non-nullable class field.
+
 ## 5.0.1
 * [Fix](https://github.com/numen31337/copy_with_extension/issues/72) Warnings when using the `?` operator on a dynamic type.
 * [Fix](https://github.com/numen31337/copy_with_extension/issues/75) Warnings when using the `!` operator on a non-nullable type.
diff --git a/copy_with_extension/pubspec.yaml b/copy_with_extension/pubspec.yaml
index f7af70b..1121e1f 100644
--- a/copy_with_extension/pubspec.yaml
+++ b/copy_with_extension/pubspec.yaml
@@ -1,5 +1,5 @@
 name: copy_with_extension
-version: 5.0.1
+version: 5.0.2
 description: Annotation for generating `copyWith` extensions code using `copy_with_extension_gen`.
 homepage: https://github.com/numen31337/copy_with_extension/tree/master/copy_with_extension
 repository: https://github.com/numen31337/copy_with_extension
diff --git a/copy_with_extension_gen/CHANGELOG.md b/copy_with_extension_gen/CHANGELOG.md
index e0a165b..4096a13 100644
--- a/copy_with_extension_gen/CHANGELOG.md
+++ b/copy_with_extension_gen/CHANGELOG.md
@@ -1,3 +1,6 @@
+## 5.0.2
+* [Fix](https://github.com/numen31337/copy_with_extension/issues/79) Allow having a nullable constructor parameter with a fallback for a non-nullable class field.
+
 ## 5.0.1
 * [Fix](https://github.com/numen31337/copy_with_extension/issues/72) Warnings when using the `?` operator on a dynamic type.
 * [Fix](https://github.com/numen31337/copy_with_extension/issues/75) Warnings when using the `!` operator on a non-nullable type.
diff --git a/copy_with_extension_gen/lib/src/copy_with_generator.dart b/copy_with_extension_gen/lib/src/copy_with_generator.dart
index 9e39ecd..0ab7be7 100644
--- a/copy_with_extension_gen/lib/src/copy_with_generator.dart
+++ b/copy_with_extension_gen/lib/src/copy_with_generator.dart
@@ -38,9 +38,10 @@ class CopyWithGenerator extends GeneratorForAnnotation<CopyWith> {
 
     for (final field in sortedFields) {
       if (field.classFieldInfo != null &&
-          field.nullable != field.classFieldInfo?.nullable) {
+          field.nullable == false &&
+          field.classFieldInfo?.nullable == true) {
         throw InvalidGenerationSourceError(
-          'The nullability of the constructor parameter "${field.name}" does not match the nullability of the corresponding field in the object.',
+          'The constructor parameter "${field.name}" is not nullable, whereas the corresponding class field is nullable. This use case is not supported.',
           element: element,
         );
       }
diff --git a/copy_with_extension_gen/pubspec.yaml b/copy_with_extension_gen/pubspec.yaml
index e69eae8..3b156a0 100644
--- a/copy_with_extension_gen/pubspec.yaml
+++ b/copy_with_extension_gen/pubspec.yaml
@@ -1,5 +1,5 @@
 name: copy_with_extension_gen
-version: 5.0.1
+version: 5.0.2
 description: Automatically generating `copyWith` extensions code for classes with `@CopyWith()` annotation.
 repository: https://github.com/numen31337/copy_with_extension
 homepage: https://github.com/numen31337/copy_with_extension/tree/master/copy_with_extension_gen
diff --git a/copy_with_extension_gen/test/gen_nullability_test.dart b/copy_with_extension_gen/test/gen_nullability_test.dart
index 5dfb266..35c00dc 100644
--- a/copy_with_extension_gen/test/gen_nullability_test.dart
+++ b/copy_with_extension_gen/test/gen_nullability_test.dart
@@ -5,10 +5,8 @@ part 'gen_nullability_test.g.dart';
 
 @CopyWith()
 class TestNullability {
-  TestNullability(
-    this.dynamicField,
-    this.integers,
-  );
+  TestNullability(this.dynamicField, this.integers, {int? constructorFallback})
+      : constructorFallback = constructorFallback ?? 0;
 
   /// https://github.com/numen31337/copy_with_extension/issues/74
   /// Test for crash on `instance.dynamicField!`.
@@ -18,6 +16,10 @@ class TestNullability {
   /// Warnings during compilation when using `!` on non-nullable value.
   /// Use `dart run copy_with_extension_gen/test/gen_nullability_test.dart` to reproduce the warning.
   final List<int> integers;
+
+  /// https://github.com/numen31337/copy_with_extension/issues/79
+  /// Case when a class has non-nullable type, but the constructor accepts nullable and falls back.
+  final int constructorFallback;
 }
 
 void main() {
@@ -30,5 +32,21 @@ void main() {
     expect(TestNullability(null, [1]).copyWith.dynamicField(1).dynamicField, 1);
     expect(
         TestNullability(null, [1]).copyWith.integers([2]).dynamicField, null);
+
+    // Test fallback is working
+    expect(
+        TestNullability(1, [1], constructorFallback: 1).constructorFallback, 1);
+    expect(
+        TestNullability(1, [1], constructorFallback: 1)
+            .copyWith
+            .constructorFallback(null)
+            .constructorFallback,
+        0);
+    expect(
+        TestNullability(1, [1], constructorFallback: 1)
+            .copyWith
+            .constructorFallback(2)
+            .constructorFallback,
+        2);
   });
 }
diff --git a/copy_with_extension_gen/test/generated_code_test_cases/test_cases_exceptions.dart b/copy_with_extension_gen/test/generated_code_test_cases/test_cases_exceptions.dart
index 553cd65..dab06a6 100644
--- a/copy_with_extension_gen/test/generated_code_test_cases/test_cases_exceptions.dart
+++ b/copy_with_extension_gen/test/generated_code_test_cases/test_cases_exceptions.dart
@@ -26,7 +26,7 @@ class NoDefaultConstructor {
 }
 
 @ShouldThrow(
-  'The nullability of the constructor parameter "nullableWithNonNullableConstructor" does not match the nullability of the corresponding field in the object.',
+  'The constructor parameter "nullableWithNonNullableConstructor" is not nullable, whereas the corresponding class field is nullable. This use case is not supported.',
 )
 @CopyWith()
 class TestNullability {