diff --git a/apps/dav/lib/CalDAV/CalDavBackend.php b/apps/dav/lib/CalDAV/CalDavBackend.php
index 165c62b503596..2342d1e94310c 100644
--- a/apps/dav/lib/CalDAV/CalDavBackend.php
+++ b/apps/dav/lib/CalDAV/CalDavBackend.php
@@ -3569,9 +3569,9 @@ protected function purgeCalendarInvitations(int $calendarId): void {
 		// delete all links that match object uid's
 		$cmd = $this->db->getQueryBuilder();
 		$cmd->delete($this->dbObjectInvitationsTable)
-			->where($cmd->expr()->in('uid', $cmd->createNamedParameter('uids'), IQueryBuilder::PARAM_STR_ARRAY));
-		foreach (array_chunk($allIds, 1000) as $chunckIds) {
-			$cmd->setParameter('uids', $chunckIds, IQueryBuilder::PARAM_INT_ARRAY);
+			->where($cmd->expr()->in('uid', $cmd->createParameter('uids'), IQueryBuilder::PARAM_STR_ARRAY));
+		foreach (array_chunk($allIds, 1000) as $chunkIds) {
+			$cmd->setParameter('uids', $chunkIds, IQueryBuilder::PARAM_STR_ARRAY);
 			$cmd->executeStatement();
 		}
 	}
@@ -3588,7 +3588,7 @@ protected function purgeCalendarInvitations(int $calendarId): void {
 	protected function purgeObjectInvitations(string $eventId): void {
 		$cmd = $this->db->getQueryBuilder();
 		$cmd->delete($this->dbObjectInvitationsTable)
-			->where($cmd->expr()->eq('uid', $cmd->createNamedParameter($eventId)));
+			->where($cmd->expr()->eq('uid', $cmd->createNamedParameter($eventId, IQueryBuilder::PARAM_STR), IQueryBuilder::PARAM_STR));
 		$cmd->executeStatement();
 	}
 }