diff --git a/www/common/cryptpad-common.js b/www/common/cryptpad-common.js
index 25f21e435..06f5e7ec8 100644
--- a/www/common/cryptpad-common.js
+++ b/www/common/cryptpad-common.js
@@ -884,7 +884,7 @@ define([
             if (typeof(Worker) === "undefined") {
                 Feedback.send('NO_WEBWORKER');
             }
-            if (typeof(ServiceWorker) === "undefined") {
+            if (!('serviceWorker' in navigator)) {
                 Feedback.send('NO_SERVICEWORKER');
             }
             if (!common.hasCSSVariables()) {