diff --git a/README.md b/README.md
index e5e6590..334c271 100644
--- a/README.md
+++ b/README.md
@@ -21,21 +21,20 @@ function getIPs(callback){
     var RTCPeerConnection = window.RTCPeerConnection
         || window.mozRTCPeerConnection
         || window.webkitRTCPeerConnection;
+    var useWebKit = !!window.webkitRTCPeerConnection;
 
     //bypass naive webrtc blocking
-    if (!RTCPeerConnection) {
+    if(!RTCPeerConnection){
         var iframe = document.createElement('iframe');
         //invalidate content script
         iframe.sandbox = 'allow-same-origin';
         iframe.style.display = 'none';
         document.body.appendChild(iframe);
         var win = iframe.contentWindow;
-        window.RTCPeerConnection = win.RTCPeerConnection;
-        window.mozRTCPeerConnection = win.mozRTCPeerConnection;
-        window.webkitRTCPeerConnection = win.webkitRTCPeerConnection;
-        RTCPeerConnection = window.RTCPeerConnection
-            || window.mozRTCPeerConnection
-            || window.webkitRTCPeerConnection;
+        RTCPeerConnection = win.RTCPeerConnection
+            || win.mozRTCPeerConnection
+            || win.webkitRTCPeerConnection;
+        useWebKit = !!win.webkitRTCPeerConnection;
     }
 
     //minimal requirements for data connection
@@ -49,7 +48,7 @@ function getIPs(callback){
     var servers = undefined;
 
     //add same stun server for chrome
-    if(window.webkitRTCPeerConnection)
+    if(useWebKit)
         servers = {iceServers: [{urls: "stun:stun.services.mozilla.com"}]};
 
     //construct a new RTCPeerConnection
@@ -87,11 +86,11 @@ function getIPs(callback){
     }, function(){});
 
     //wait for a while to let everything done
-    setTimeout(function() {
+    setTimeout(function(){
         //read candidate info from local description
         var lines = pc.localDescription.sdp.split('\n');
 
-        lines.forEach(function(line) {
+        lines.forEach(function(line){
             if(line.indexOf('a=candidate:') === 0){
                 handleCandidate(line);
             }
diff --git a/index.html b/index.html
index 6993167..667c1c6 100644
--- a/index.html
+++ b/index.html
@@ -28,21 +28,20 @@
                 var RTCPeerConnection = window.RTCPeerConnection
                     || window.mozRTCPeerConnection
                     || window.webkitRTCPeerConnection;
+                var useWebKit = !!window.webkitRTCPeerConnection;
 
                 //bypass naive webrtc blocking
-                if (!RTCPeerConnection) {
+                if(!RTCPeerConnection){
                     var iframe = document.createElement('iframe');
                     //invalidate content script
                     iframe.sandbox = 'allow-same-origin';
                     iframe.style.display = 'none';
                     document.body.appendChild(iframe);
                     var win = iframe.contentWindow;
-                    window.RTCPeerConnection = win.RTCPeerConnection;
-                    window.mozRTCPeerConnection = win.mozRTCPeerConnection;
-                    window.webkitRTCPeerConnection = win.webkitRTCPeerConnection;
-                    RTCPeerConnection = window.RTCPeerConnection
-                        || window.mozRTCPeerConnection
-                        || window.webkitRTCPeerConnection;
+                    RTCPeerConnection = win.RTCPeerConnection
+                        || win.mozRTCPeerConnection
+                        || win.webkitRTCPeerConnection;
+                    useWebKit = !!win.webkitRTCPeerConnection;
                 }
 
                 //minimal requirements for data connection
@@ -56,7 +55,7 @@
                 var servers = undefined;
 
                 //add same stun server for chrome
-                if(window.webkitRTCPeerConnection)
+                if(useWebKit)
                     servers = {iceServers: [{urls: "stun:stun.services.mozilla.com"}]};
 
                 //construct a new RTCPeerConnection