diff --git a/djangorestframework/resources.py b/djangorestframework/resources.py
index 561289fc0..cc338cc05 100644
--- a/djangorestframework/resources.py
+++ b/djangorestframework/resources.py
@@ -309,11 +309,14 @@ class ModelResource(FormResource):
             return None
 
         # Instantiate the ModelForm as appropriate
-        form_kwargs = {'data': data, 'files': files}
-         # Bound to an existing model instance
-        if hasattr(self.view, 'model_instance'): form_kwargs['instance'] = self.view.model_instance
+        if data is not None or files is not None:
+            if issubclass(form, forms.ModelForm) and hasattr(self.view, 'model_instance'):
+                # Bound to an existing model instance
+                return form(data, files, instance=self.view.model_instance)
+            else:
+                return form(data, files)
 
-        return form(**form_kwargs)
+        return form()
 
     def url(self, instance):
         """