diff --git a/typo3/sysext/core/Classes/Resource/Collection/AbstractFileCollection.php b/typo3/sysext/core/Classes/Resource/Collection/AbstractFileCollection.php
index a894527ca44fe926629235db3f1638c6cfc490c3..6f145982416d88264e964cc2fa6e4cebd546fb99 100644
--- a/typo3/sysext/core/Classes/Resource/Collection/AbstractFileCollection.php
+++ b/typo3/sysext/core/Classes/Resource/Collection/AbstractFileCollection.php
@@ -79,6 +79,7 @@ abstract class AbstractFileCollection extends AbstractRecordCollection
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function key()
     {
         /** @var File $currentRecord */