diff --git a/code_generator/lib/src/fields/asset_field.dart b/code_generator/lib/src/fields/asset_field.dart
index 5bd2b48..62545c7 100644
--- a/code_generator/lib/src/fields/asset_field.dart
+++ b/code_generator/lib/src/fields/asset_field.dart
@@ -24,6 +24,11 @@ base class AssetField extends BaseField {
   );
 
   @override
-  Expression buildInitializer(CodeExpression valueExpression) =>
-      initializerFromRequired(isRequired, valueExpression, type.nonNullable.invokeNamed("fromJson", valueExpression));
+  Expression buildInitializer(CodeExpression valueExpression) {
+    if (isRequired) return type.nonNullable.invokeNamed("fromJson", valueExpression);
+    return valueExpression
+        .equalTo(literalNull)
+        .or(valueExpression.index(literalString('filename')).equalTo(literalNull))
+        .conditional(literalNull, type.nonNullable.invokeNamed("fromJson", valueExpression));
+  }
 }
diff --git a/code_generator/test/field_test.dart b/code_generator/test/field_test.dart
index 94938c9..58aa594 100644
--- a/code_generator/test/field_test.dart
+++ b/code_generator/test/field_test.dart
@@ -689,7 +689,8 @@ void main() {
       );
       expect(
         field.buildInitializer(valueExpression.expression),
-        emitter.equalsCode("$valueExpression == null ? null : Asset.fromJson($valueExpression)"),
+        emitter.equalsCode(
+            "$valueExpression == null || $valueExpression [ 'filename' ] == null ? null : Asset.fromJson($valueExpression)"),
       );
     });
     test("Test required asset", () {