diff --git a/lib/Controller/MentionController.php b/lib/Controller/MentionController.php
index 3269acc76d..afd93b7d6a 100644
--- a/lib/Controller/MentionController.php
+++ b/lib/Controller/MentionController.php
@@ -16,6 +16,7 @@
 use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\Files\IRootFolder;
 use OCP\IRequest;
+use OCP\IUserManager;
 use OCP\Notification\IManager;
 
 class MentionController extends Controller {
@@ -25,6 +26,7 @@ public function __construct(
 		private IRootFolder $rootFolder,
 		private IManager $manager,
 		private ITimeFactory $timeFactory,
+		private IUserManager $userManager,
 		private ?string $userId,
 	) {
 		parent::__construct($appName, $request);
@@ -46,7 +48,7 @@ public function mention(int $fileId, string $mention): DataResponse {
 		}
 
 		$notification = $this->manager->createNotification();
-		$notification->setUser($mention)
+		$notification->setUser($user->getUID())
 			->setApp(Application::APPNAME)
 			->setSubject(Notifier::TYPE_MENTIONED, [
 				Notifier::SUBJECT_MENTIONED_SOURCE_USER => $this->userId,
@@ -58,7 +60,6 @@ public function mention(int $fileId, string $mention): DataResponse {
 			$notification->setDateTime(\DateTime::createFromImmutable($this->timeFactory->now()));
 			$this->manager->notify($notification);
 			return new DataResponse([], Http::STATUS_OK);
-
 		}
 
 		return new DataResponse([], Http::STATUS_NOT_FOUND);