diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index cd45bafeb99..559c41b6e82 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -3259,7 +3259,7 @@ PyTypeObject PySuper_Type = {
 	super_getattro,				/* tp_getattro */
 	0,					/* tp_setattro */
 	0,					/* tp_as_buffer */
-	Py_TPFLAGS_DEFAULT,			/* tp_flags */
+	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
  	super_doc,				/* tp_doc */
  	0,					/* tp_traverse */
  	0,					/* tp_clear */