Intern the strings "__builtins__".
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index e416b4f..546f1e8 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -147,7 +147,7 @@
 	frameobject *f;
 	object *builtins;
 	if (builtin_object == NULL) {
-		builtin_object = newstringobject("__builtins__");
+		builtin_object = PyString_InternFromString("__builtins__");
 		if (builtin_object == NULL)
 			return NULL;
 	}