diff --git a/app/adapters/web-extension.js b/app/adapters/web-extension.js
index e7db10a6b1..516b4b53e2 100644
--- a/app/adapters/web-extension.js
+++ b/app/adapters/web-extension.js
@@ -53,8 +53,12 @@ export default BasicAdapter.extend({
   },
 
   _injectDebugger() {
-    loadEmberDebug().then((emberDebug) => {
-      chrome.devtools.inspectedWindow.eval(emberDebug);
+    loadEmberDebug().then(emberDebug => {
+      chrome.devtools.inspectedWindow.eval(emberDebug, (success, error) => {
+        if (success === undefined && error) {
+          throw error;
+        }
+      });
       this.onResourceAdded();
     });
   },
@@ -96,7 +100,10 @@ export default BasicAdapter.extend({
    * @param {String} goToVersion
    */
   onVersionMismatch(goToVersion) {
-    window.location.href = `../panes-${goToVersion.replace(/\./g, '-')}/index.html`;
+    window.location.href = `../panes-${goToVersion.replace(
+      /\./g,
+      '-'
+    )}/index.html`;
   },
 
   /**
@@ -104,16 +111,15 @@ export default BasicAdapter.extend({
     scripts as soon as possible into the new page.
   */
   reloadTab() {
-    loadEmberDebug().then((emberDebug) => {
+    loadEmberDebug().then(emberDebug => {
       chrome.devtools.inspectedWindow.reload({ injectedScript: emberDebug });
     });
-
   },
 
   canOpenResource: false,
 
   sendIframes(urls) {
-    loadEmberDebug().then((emberDebug) => {
+    loadEmberDebug().then(emberDebug => {
       urls.forEach(url => {
         chrome.devtools.inspectedWindow.eval(emberDebug, { frameURL: url });
       });
@@ -124,7 +130,7 @@ export default BasicAdapter.extend({
 function loadEmberDebug() {
   let minimumVersion = config.emberVersionsSupported[0].replace(/\./g, '-');
   let xhr;
-  return new Promise((resolve) => {
+  return new Promise(resolve => {
     if (!emberDebug) {
       xhr = new XMLHttpRequest();
       xhr.open("GET", chrome.runtime.getURL(`/panes-${minimumVersion}/ember_debug.js`));
diff --git a/ember_debug/vendor/startup-wrapper.js b/ember_debug/vendor/startup-wrapper.js
index 0583377260..f294f6a827 100644
--- a/ember_debug/vendor/startup-wrapper.js
+++ b/ember_debug/vendor/startup-wrapper.js
@@ -24,9 +24,6 @@ var EMBER_VERSIONS_SUPPORTED = {{EMBER_VERSIONS_SUPPORTED}};
 // @formatter:on
 
 (function(adapter) {
-  var onReady = requireModule('ember-debug/utils/on-ready').onReady;
-  var compareVersion = requireModule('ember-debug/utils/version').compareVersion;
-
   onEmberReady(function() {
     // global to prevent injection
     if (window.NO_EMBER_DEBUG) {
@@ -219,6 +216,12 @@ var EMBER_VERSIONS_SUPPORTED = {{EMBER_VERSIONS_SUPPORTED}};
     });
   }
 
+  let channel = new MessageChannel();
+  let port = channel.port1;
+  window.postMessage('debugger-client', '*', [channel.port2]);
+
+  let registeredMiss = false;
+
   /**
    * This function is called if the app's Ember version
    * is not supported by this version of the inspector.
@@ -227,16 +230,24 @@ var EMBER_VERSIONS_SUPPORTED = {{EMBER_VERSIONS_SUPPORTED}};
    * to an inspector version that supports this Ember version.
    */
   function sendVersionMiss() {
-    var adapter = requireModule('ember-debug/adapters/' + currentAdapter)['default'].create();
-    adapter.onMessageReceived(function(message) {
+    if (registeredMiss) {
+      return;
+    }
+
+    registeredMiss = true;
+
+    port.addEventListener('message', message => {
       if (message.type === 'check-version') {
         sendVersionMismatch();
       }
     });
+
     sendVersionMismatch();
 
+    port.start();
+
     function sendVersionMismatch() {
-      adapter.sendMessage({
+      port.postMessage({
         name: 'version-mismatch',
         version: Ember.VERSION,
         from: 'inspectedWindow'
@@ -277,4 +288,74 @@ var EMBER_VERSIONS_SUPPORTED = {{EMBER_VERSIONS_SUPPORTED}};
     return !toVersion || compareVersion(version, toVersion) === -1;
   }
 
+  function onReady(callback) {
+    if (document.readyState === 'complete' || document.readyState === 'interactive') {
+      setTimeout(completed);
+    } else {
+      document.addEventListener("DOMContentLoaded", completed, false);
+      // For some reason DOMContentLoaded doesn't always work
+      window.addEventListener("load", completed, false);
+    }
+
+    function completed() {
+      document.removeEventListener("DOMContentLoaded", completed, false);
+      window.removeEventListener("load", completed, false);
+      callback();
+    }
+  }
+
+  /**
+   * Compares two Ember versions.
+   *
+   * Returns:
+   * `-1` if version1 < version
+   * 0 if version1 == version2
+   * 1 if version1 > version2
+   *
+   * @param {String} version1
+   * @param {String} version2
+   * @return {Boolean} result of the comparison
+   */
+  function compareVersion(version1, version2) {
+    let compared, i;
+    version1 = cleanupVersion(version1).split('.');
+    version2 = cleanupVersion(version2).split('.');
+    for (i = 0; i < 3; i++) {
+      compared = compare(+version1[i], +version2[i]);
+      if (compared !== 0) {
+        return compared;
+      }
+    }
+    return 0;
+  }
+
+  /**
+   * Remove -alpha, -beta, etc from versions
+   *
+   * @param {String} version
+   * @return {String} The cleaned up version
+   */
+  function cleanupVersion(version) {
+    return version.replace(/-.*/g, '');
+  }
+
+  /**
+   * @method compare
+   * @param {Number} val
+   * @param {Number} number
+   * @return {Number}
+   *  0: same
+   * -1: <
+   *  1: >
+   */
+  function compare(val, number) {
+    if (val === number) {
+      return 0;
+    } else if (val < number) {
+      return -1;
+    } else if (val > number) {
+      return 1;
+    }
+  }
+
 }(currentAdapter));
diff --git a/skeletons/web-extension/content-script.js b/skeletons/web-extension/content-script.js
index 4cd952141a..fabac55719 100644
--- a/skeletons/web-extension/content-script.js
+++ b/skeletons/web-extension/content-script.js
@@ -61,8 +61,6 @@
     document.documentElement.dataset.emberExtension = 1;
   }
 
-
-
   // Iframes should not reset the icon so we make sure
   // it's the top level window before resetting.
   if (window.top === window) {
@@ -70,7 +68,6 @@
     chrome.runtime.sendMessage({ type: 'resetEmberIcon' });
   }
 
-
   /**
    * Inject JS into the page to check for an app on domready.  The in-page-script
    * is used by all variants of ember-inspector (Chrome, FF, Bookmarklet) to get
@@ -91,7 +88,7 @@
    */
   var iframes = document.getElementsByTagName('iframe');
   var urls = [];
-  for (var i = 0, l = iframes.length; i < l; i ++) {
+  for (var i = 0, l = iframes.length; i < l; i++) {
     urls.push(iframes[i].src);
   }
 
@@ -103,6 +100,4 @@
   setTimeout(function() {
     chrome.runtime.sendMessage({type: 'iframes', urls: urls});
   }, 500);
-
-
-}());
+})();
diff --git a/skeletons/web-extension/manifest.json b/skeletons/web-extension/manifest.json
index f667bf569f..8ef825084c 100644
--- a/skeletons/web-extension/manifest.json
+++ b/skeletons/web-extension/manifest.json
@@ -18,7 +18,7 @@
     "contextMenus"
   ],
 
-  "content_security_policy": "script-src 'self'; object-src 'self'",
+  "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self'",
   "devtools_page": "devtools.html",
 
   "content_scripts": [{