Index: django/forms/models.py
===================================================================
--- django/forms/models.py	(revision 9805)
+++ django/forms/models.py	(working copy)
@@ -493,10 +493,9 @@
         fk_attname = self.fk.get_attname()
         kwargs = {fk_attname: self.instance.pk}
         new_obj = self.model(**kwargs)
+        exclude = [self.fk.name, fk_attname]
         if fk_attname == self._pk_field.attname:
-            exclude =  [self._pk_field.name]
-        else:
-            exclude = []
+            exclude.append(self._pk_field.name)
         return save_instance(form, new_obj, exclude=exclude, commit=commit)
 
     def add_fields(self, form, index):