diff --git a/lib/Notification/Notifier.php b/lib/Notification/Notifier.php
index 0a9425828..e86b9bfb1 100644
--- a/lib/Notification/Notifier.php
+++ b/lib/Notification/Notifier.php
@@ -239,8 +239,8 @@ public function prepare(INotification $notification, string $languageCode): INot
 						],
 						'user' => [
 							'type' => 'user',
-							'id' => $params[1],
-							'name' => $dn,
+							'id' => $params[1] ?? '',
+							'name' => $dn ?? '',
 						]
 					]
 				);