diff --git a/apps/files/lib/Activity/FavoriteProvider.php b/apps/files/lib/Activity/FavoriteProvider.php
index 84c509f493ff1..7a660287192ae 100644
--- a/apps/files/lib/Activity/FavoriteProvider.php
+++ b/apps/files/lib/Activity/FavoriteProvider.php
@@ -138,7 +138,7 @@ protected function setSubjects(IEvent $event, $subject) {
 		}
 		$parameter = [
 			'type' => 'file',
-			'id' => $subjectParams['id'],
+			'id' => (string)$subjectParams['id'],
 			'name' => basename($subjectParams['path']),
 			'path' => trim($subjectParams['path'], '/'),
 			'link' => $this->url->linkToRouteAbsolute('files.viewcontroller.showFile', ['fileid' => $subjectParams['id']]),