diff --git a/src/core/observer/traverse.js b/src/core/observer/traverse.js
index ca6c314eb76..37c71e9cf98 100644
--- a/src/core/observer/traverse.js
+++ b/src/core/observer/traverse.js
@@ -18,7 +18,7 @@ export function traverse (val: any) {
 function _traverse (val: any, seen: SimpleSet) {
   let i, keys
   const isA = Array.isArray(val)
-  if ((!isA && !isObject(val)) || !Object.isExtensible(val)) {
+  if ((!isA && !isObject(val)) || Object.isFrozen(val)) {
     return
   }
   if (val.__ob__) {