diff --git a/src/observer/index.js b/src/observer/index.js
index a1198ccb..c7b55ca7 100644
--- a/src/observer/index.js
+++ b/src/observer/index.js
@@ -3,6 +3,7 @@ import { arrayMethods } from './array'
 import {
   def,
   isArray,
+  isObject,
   isPlainObject,
   hasProto,
   hasOwn
@@ -160,7 +161,7 @@ function copyAugment (target, src, keys) {
  */
 
 export function observe (value, vm) {
-  if (!value || typeof value !== 'object') {
+  if (!isObject(value)) {
     return
   }
   var ob
diff --git a/src/vdom/modules/class.js b/src/vdom/modules/class.js
index 33774ddd..d2822b94 100644
--- a/src/vdom/modules/class.js
+++ b/src/vdom/modules/class.js
@@ -1,10 +1,10 @@
-import { isArray, setClass } from '../../util/index'
+import { isArray, isObject, setClass } from '../../util/index'
 
 function genClass (data) {
   if (!data) {
     return ''
   }
-  if (typeof data === 'object') {
+  if (isObject(data)) {
     let res = ''
     for (var key in data) {
       if (data[key]) res += key + ' '