diff --git a/js/ui/endSessionDialog.js b/js/ui/endSessionDialog.js
index 0b475b6f9..f51eb7bee 100644
--- a/js/ui/endSessionDialog.js
+++ b/js/ui/endSessionDialog.js
@@ -352,12 +352,15 @@ class EndSessionDialog extends ModalDialog.ModalDialog {
         }
 
         // It only makes sense to check for this permission if PackageKit is available.
-        try {
-            this._updatesPermission = Polkit.Permission.new_sync(
-                'org.freedesktop.packagekit.trigger-offline-update', null, null);
-        } catch (e) {
-            log('No permission to trigger offline updates: %s'.format(e.toString()));
-        }
+        Polkit.Permission.new(
+            'org.freedesktop.packagekit.trigger-offline-update', null, null,
+            (source, res) => {
+                try {
+                    this._updatesPermission = Polkit.Permission.new_finish(res);
+                } catch (e) {
+                    log(`No permission to trigger offline updates: ${e}`);
+                }
+            });
     }
 
     _onDestroy() {