diff --git a/packager/debugger.html b/packager/debugger.html
index d72e40ead23b..35ea4b84a687 100644
--- a/packager/debugger.html
+++ b/packager/debugger.html
@@ -31,31 +31,28 @@
   document.getElementById('status').innerHTML = status;
 }
 
+// This worker will run the application javascript code,
+// making sure that it's run in an environment without a global
+// document, to make it consistent with the JSC executor environment.
+var worker = new Worker('debuggerWorker.js');
+
 var messageHandlers = {
   // This method is a bit hacky. Catalyst asks for a new clean JS runtime.
   // The easiest way to do this is to reload this page. That also means that
   // web socket connection will be lost. To send reply back we need to remember
-  // message id
+  // message id.
+  // This message also needs to be handled outside of the worker, since the worker
+  // doesn't have access to local storage.
   'prepareJSRuntime': function(message) {
     window.onbeforeunload = undefined;
     window.localStorage.setItem('sessionID', message.id);
     window.location.reload();
   },
-  'executeApplicationScript': function(message, sendReply) {
-    for (var key in message.inject) {
-      window[key] = JSON.parse(message.inject[key]);
-    }
-    loadScript(message.url, sendReply.bind(null, null));
+  'executeApplicationScript': function(message) {
+    worker.postMessage(message);
   },
-  'executeJSCall': function(message, sendReply) {
-    var returnValue = [[], [], [], [], []];
-    try {
-      if (window && window.require) {
-        returnValue = window.require(message.moduleName)[message.moduleMethod].apply(null, message.arguments);
-      }
-    } finally {
-      sendReply(JSON.stringify(returnValue));
-    }
+  'executeJSCall': function(message){
+    worker.postMessage(message);
   }
 }
 
@@ -72,12 +69,10 @@
 
 ws.onmessage = function(message) {
   var object = JSON.parse(message.data);
-  var sendReply = function(result) {
-    ws.send(JSON.stringify({replyID: object.id, result: result}));
-  }
   var handler = messageHandlers[object.method];
+
   if (handler) {
-    handler(object, sendReply);
+    handler(object);
   } else {
     console.warn('Unknown method: ' + object.method);
   }
@@ -87,12 +82,8 @@
   setStatus('Disconnected from proxy. Is node server running?');
 }
 
-function loadScript(src, callback) {
-  var script = document.createElement('script');
-  script.type = 'text/javascript';
-  script.src = src;
-  script.onload = callback;
-  document.head.appendChild(script);
+worker.onmessage = function(message) {
+  ws.send(JSON.stringify(message.data));
 }
 
 })();
diff --git a/packager/debuggerWorker.js b/packager/debuggerWorker.js
new file mode 100644
index 000000000000..506a0a0e8162
--- /dev/null
+++ b/packager/debuggerWorker.js
@@ -0,0 +1,39 @@
+
+var messageHandlers = {
+  'executeApplicationScript': function(message, sendReply) {
+    for (var key in message.inject) {
+      self[key] = JSON.parse(message.inject[key]);
+    }
+    loadScript(message.url, sendReply.bind(null, null));
+  },
+  'executeJSCall': function(message, sendReply) {
+    var returnValue = [[], [], [], [], []];
+    try {
+      if (require) {
+        returnValue = require(message.moduleName)[message.moduleMethod].apply(null, message.arguments);
+      }
+    } finally {
+      sendReply(JSON.stringify(returnValue));
+    }
+  }
+}
+
+onmessage = function(message) {
+  var object = message.data;
+
+  var sendReply = function(result) {
+     postMessage({replyID: object.id, result: result});
+  }
+
+  var handler = messageHandlers[object.method];
+  if (handler) {
+    handler(object, sendReply);
+  } else {
+    console.warn('Unknown method: ' + object.method);
+  }
+}
+
+function loadScript(src, callback) {
+  importScripts(src);
+  callback();
+}
diff --git a/packager/packager.js b/packager/packager.js
index 7dd013c67c7d..6978b5fcc2bc 100644
--- a/packager/packager.js
+++ b/packager/packager.js
@@ -171,6 +171,10 @@ function getDevToolsLauncher(options) {
       var debuggerPath = path.join(__dirname, 'debugger.html');
       res.writeHead(200, {'Content-Type': 'text/html'});
       fs.createReadStream(debuggerPath).pipe(res);
+    } else if (req.url === '/debuggerWorker.js') {
+      var workerPath = path.join(__dirname, 'debuggerWorker.js');
+      res.writeHead(200, {'Content-Type': 'application/javascript'});
+      fs.createReadStream(workerPath).pipe(res);
     } else if (req.url === '/launch-chrome-devtools') {
       var debuggerURL = 'http://localhost:' + options.port + '/debugger-ui';
       var script = 'launchChromeDevTools.applescript';