diff --git a/Classes/Driver/AmazonS3Driver.php b/Classes/Driver/AmazonS3Driver.php
index 4d351a91..cbb3cd84 100644
--- a/Classes/Driver/AmazonS3Driver.php
+++ b/Classes/Driver/AmazonS3Driver.php
@@ -1487,7 +1487,7 @@ protected function resetIdentifierMap()
     protected function getSubObjects($identifier, $recursive = true, $filter = self::FILTER_ALL)
     {
         $result = $this->getListObjects($identifier);
-        if (!is_array($result['Contents'])) {
+        if (!is_array($result['Contents'] ?? null)) {
             return [];
         }
         return array_filter($result['Contents'], function (&$object) use ($identifier, $recursive, $filter) {