diff --git a/src/puppet-web-injectio.js b/src/puppet-web-injectio.js
index 94bc11ea07ef908c3f4805fb37843791c10100b9..3e498b2eb9bfca349c2bd711acaecffb0c9222f6 100644
--- a/src/puppet-web-injectio.js
+++ b/src/puppet-web-injectio.js
@@ -176,8 +176,7 @@ return (function(port) {
     // 408: 未确认
     var code  = +Wechaty.glue.loginScope.code
     var url   =  Wechaty.glue.loginScope.qrcodeUrl
-    if (typeof code !== 'undefined' && code !== null
-      && code !== Wechaty.vars.scanCode) {
+    if (url && code !== Wechaty.vars.scanCode) {
 
       log('checkScan() - code change detected. from '
         + Wechaty.vars.scanCode