diff --git a/skeletons/web-extension/scripts/in-page-script.js b/skeletons/web-extension/scripts/in-page-script.js
index 7846c92ec4..ee607b092a 100644
--- a/skeletons/web-extension/scripts/in-page-script.js
+++ b/skeletons/web-extension/scripts/in-page-script.js
@@ -29,9 +29,17 @@
   onReady(function() {
     var libraries = window.Ember && window.Ember.libraries;
     if (libraries) {
+      // Ember has changed where the array of libraries is located.
+      // In older versions, `Ember.libraries` was the array itself,
+      // but now it's found under _registry.
+      if (libraries._registry) {
+        libraries = libraries._registry;
+      }
+
+      var versions = Array.prototype.slice.call(libraries, 0);
       window.postMessage({
         type: 'emberVersion',
-        versions: libraries._registry.slice()
+        versions: versions
       }, '*');
     }
   });