diff --git a/lib/Controller/PublicSessionController.php b/lib/Controller/PublicSessionController.php
index 015f5c0a7b7..dbf9a2642bd 100644
--- a/lib/Controller/PublicSessionController.php
+++ b/lib/Controller/PublicSessionController.php
@@ -80,7 +80,7 @@ public function create(string $token, string $file = null, $guestName = null, bo
 	 * @NoAdminRequired
 	 * @PublicPage
 	 */
-	public function fetch(int $documentId, string $sessionId, string $sessionToken): Response {
+	public function fetch(int $documentId, int $sessionId, string $sessionToken): Response {
 		return $this->apiService->fetch($documentId, $sessionId, $sessionToken);
 	}