diff --git a/django/db/models/query.py b/django/db/models/query.py
index 57e41fc608..710d4a75cc 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -41,7 +41,7 @@ class _QuerySet(object):
             else:
                 self._result_cache = list(self.iterator())
         elif self._iter:
-            self.result_cache.extend(list(self._iter))
+            self._result_cache.extend(list(self._iter))
         return len(self._result_cache)
 
     def __iter__(self):