diff --git a/lighthouse-core/driver/gatherers/service-worker.js b/lighthouse-core/driver/gatherers/service-worker.js
index fecdd718e0b5..bd5a45087a3e 100644
--- a/lighthouse-core/driver/gatherers/service-worker.js
+++ b/lighthouse-core/driver/gatherers/service-worker.js
@@ -26,7 +26,8 @@ class ServiceWorker extends Gather {
    */
   static getOrigin(url) {
     const parsedURL = require('url').parse(url);
-    return `${parsedURL.protocol}//${parsedURL.hostname}`;
+    return `${parsedURL.protocol}//${parsedURL.hostname}` +
+        (parsedURL.port ? `:${parsedURL.port}` : '');
   }
 
   /**