diff --git a/django/db/models/query.py b/django/db/models/query.py
index 4fe185ed6e9..b08f3acd144 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -95,6 +95,8 @@ class CollectedObjects(object):
         while len(dealt_with) < len(models):
             found = False
             for model in models:
+                if model in dealt_with:
+                    continue
                 children = self.children.setdefault(model, [])
                 if len([c for c in children if c not in dealt_with]) == 0:
                     dealt_with[model] = None