diff --git a/php/elFinder.class.php b/php/elFinder.class.php
index 763b9a9bd..ab370acc6 100644
--- a/php/elFinder.class.php
+++ b/php/elFinder.class.php
@@ -4473,7 +4473,7 @@ protected function itemLock($hashes, $autoUnlock = true)
         foreach ($hashes as $hash) {
             $lock = elFinder::$commonTempPath . DIRECTORY_SEPARATOR . self::filenameDecontaminate($hash) . '.lock';
             if ($this->itemLocked($hash)) {
-                $cnt = file_get_contents($lock) + 1;
+                $cnt = (int)file_get_contents($lock) + 1;
             } else {
                 $cnt = 1;
             }