diff --git a/package.json b/package.json
index fe3995d3c12af4bc544b0086e56b933d18f4eda2..c328357aedd2c9a7788b694a3936be3bb67019ff 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "wechaty",
-  "version": "0.4.0",
+  "version": "0.5.0",
   "description": "Wechat for Bot (Personal Account)",
   "main": "index.js",
   "types": "./index.d.ts",
@@ -93,7 +93,7 @@
     "chromedriver": "^2.23.1",
     "express": "^4.13.4",
     "is-ci": "^1.0.9",
-    "phantomjs-prebuilt": "^2.1.12",
+    "phantomjs-prebuilt": "^2.1.13",
     "ps-tree": "^1.0.1",
     "retry-promise": "^1.0.0",
     "selenium-webdriver": "^3.0.0-beta-1",
diff --git a/src/puppet-web/browser.ts b/src/puppet-web/browser.ts
index cf3289cfa78d6d74897859265ae72dd3c956f0d4..f70f5613c46d78a63ed0e51322bd81edfa5bd023 100644
--- a/src/puppet-web/browser.ts
+++ b/src/puppet-web/browser.ts
@@ -168,11 +168,13 @@ export class Browser extends EventEmitter {
   public driver(newDriver: WebDriver): WebDriver
 
   public driver(newDriver?: WebDriver | null): WebDriver | void {
-    log.silly('PuppetWebBrowser', 'driver(%s)'
-                                , typeof newDriver === 'undefined'
-                                  ? ''
-                                  : newDriver
-    )
+    if (newDriver !== undefined) {
+      log.silly('PuppetWebBrowser', 'driver(%s)'
+                                  , newDriver
+                                    ? newDriver.constructor.name
+                                    : null
+      )
+    }
 
     if (typeof newDriver !== 'undefined') {
       if (newDriver) {
@@ -248,6 +250,9 @@ export class Browser extends EventEmitter {
   private getPhantomJsDriver(): WebDriver {
     // setup custom phantomJS capability https://github.com/SeleniumHQ/selenium/issues/2069
     const phantomjsExe = require('phantomjs-prebuilt').path
+    if (!phantomjsExe) {
+      throw new Error('phantomjs binary path not found')
+    }
     // const phantomjsExe = require('phantomjs2').path
 
     const phantomjsArgs = [