diff --git a/package.json b/package.json
index 757df7374383186da65801491278bd2ec1daaeb0..0d7775e912794c3770a49c88b4ed14dcebdf7533 100644
--- a/package.json
+++ b/package.json
@@ -65,6 +65,7 @@
     "cross-env": "^2.0.0",
     "eslint": "^3.3.1",
     "qrcode-terminal": "^0.10.0",
+    "sinon": "^1.17.5",
     "tape": "^4.6.0",
     "tuling123-client": "0.0.1"
   },
diff --git a/src/wechaty.js b/src/wechaty.js
index c4bcfa5ca840c23e4dace1d43a9fcb955df18666..cbffe05166943a6da31081a5b0c1493490291d36 100644
--- a/src/wechaty.js
+++ b/src/wechaty.js
@@ -25,7 +25,7 @@ class Wechaty extends EventEmitter {
     , endpoint  = process.env.WECHATY_ENDPOINT          // wechaty.io api endpoint
     , token     = process.env.WECHATY_TOKEN             // token for wechaty.io auth
     , profile   = process.env.WECHATY_PROFILE           // no profile, no session save/restore
-  }) {
+  } = {}) {
     super()
     this.type     = type
     this.head     = head