diff --git a/graphene_django/forms/mutation.py b/graphene_django/forms/mutation.py
index e8e76a2..793aafe 100644
--- a/graphene_django/forms/mutation.py
+++ b/graphene_django/forms/mutation.py
@@ -128,7 +128,7 @@ class DjangoModelFormMutation(BaseDjangoFormMutation):
 
         form = form_class()
         input_fields = fields_for_form(form, only_fields, exclude_fields)
-        input_fields['id'] = convert_form_field(model._meta.pk)
+        input_fields['id'] = graphene.ID()
 
         registry = get_global_registry()
         model_type = registry.get_type_for_model(model)
diff --git a/graphene_django/forms/tests/test_mutation.py b/graphene_django/forms/tests/test_mutation.py
index 3bfb883..10a15ae 100644
--- a/graphene_django/forms/tests/test_mutation.py
+++ b/graphene_django/forms/tests/test_mutation.py
@@ -22,7 +22,7 @@ def test_needs_form_class():
         class MyMutation(DjangoFormMutation):
             pass
 
-    assert exc.value.args[0] == 'form_class is required for FormMutation'
+    assert exc.value.args[0] == 'form_class is required for DjangoFormMutation'
 
 
 def test_has_output_fields():