diff --git a/graphene_django/rest_framework/tests/test_mutation.py b/graphene_django/rest_framework/tests/test_mutation.py
index bfe53cc..9159d32 100644
--- a/graphene_django/rest_framework/tests/test_mutation.py
+++ b/graphene_django/rest_framework/tests/test_mutation.py
@@ -104,6 +104,15 @@ def test_exclude_fields():
     assert "cool_name" in MyMutation.Input._meta.fields
     assert "created" not in MyMutation.Input._meta.fields
 
+def test_model_serializer_optional_fields():
+    class MyMutation(SerializerMutation):
+        class Meta:
+            serializer_class = MyModelSerializer
+            optional_fields = ("cool_name",)
+
+    assert "cool_name" in MyMutation.Input._meta.fields
+    assert MyMutation.Input._meta.fields["cool_name"].type == String
+
 
 def test_write_only_field():
     class WriteOnlyFieldModelSerializer(serializers.ModelSerializer):