diff --git a/django/db/models/query.py b/django/db/models/query.py
index c2e6e1808c..92d6df4fc9 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -202,6 +202,9 @@ class QuerySet(object):
         "Returns a new QuerySet instance with '_distinct' modified."
         return self._clone(_distinct=true_or_false)
 
+    def extra(self, select=None, where=None, params=None, tables=None):
+        return self._clone(_select=select, _where=where, _params=params, _tables=tables)
+
     ###################
     # PRIVATE METHODS #
     ###################
@@ -322,9 +325,6 @@ class QuerySet(object):
 #             combined._order_by = copy.deepcopy(self._order_by)
 #         return combined
 #
-#     def extras(self, params=None, select=None, where=None, tables=None):
-#         return self._clone(_params=params, _select=select, _where=where, _tables=tables)
-#
 #     def __and__(self, other):
 #         combined = self._combine(other)
 #         combined._filter = self._filter & other._filter