SF #561244: micro optimizations, builtins cannot be NULL, so use Py_INCREF
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 90cd952..c65ca40 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -287,7 +287,7 @@
 		}
 	}
 	else
-		Py_XINCREF(builtins);
+		Py_INCREF(builtins);
 	f->f_builtins = builtins;
 	Py_XINCREF(back);
 	f->f_back = back;