diff --git a/lib/private/Preview/Db/PreviewMapper.php b/lib/private/Preview/Db/PreviewMapper.php
index cf442e51691..e66e2c2ef0a 100644
--- a/lib/private/Preview/Db/PreviewMapper.php
+++ b/lib/private/Preview/Db/PreviewMapper.php
@@ -204,10 +204,10 @@ class PreviewMapper extends QBMapper {
 	/**
 	 * @return \Generator<Preview>
 	 */
-	public function getPreviews(int $lastId, int $limit = 1000): \Generator {
+	public function getPreviews(string $lastId, int $limit = 1000): \Generator {
 		$qb = $this->db->getQueryBuilder();
 		$this->joinLocation($qb)
-			->where($qb->expr()->gt('p.id', $qb->createNamedParameter($lastId, IQueryBuilder::PARAM_INT)))
+			->where($qb->expr()->gt('p.id', $qb->createNamedParameter($lastId)))
 			->setMaxResults($limit);
 		return $this->yieldEntities($qb);
 
diff --git a/lib/private/Preview/PreviewService.php b/lib/private/Preview/PreviewService.php
index c4beb67a521..3683d662ecd 100644
--- a/lib/private/Preview/PreviewService.php
+++ b/lib/private/Preview/PreviewService.php
@@ -110,7 +110,7 @@ class PreviewService {
 	 * @throws Exception
 	 */
 	public function deleteAll(): void {
-		$lastId = 0;
+		$lastId = '0';
 		while (true) {
 			$previews = $this->previewMapper->getPreviews($lastId, 1000);
 			$i = 0;