diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 77ef359..1c50986 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -1201,6 +1201,7 @@
 	VISIT(prop_get);
 	VISIT(prop_set);
 	VISIT(prop_del);
+	VISIT(prop_doc);
 
 	return 0;
 }