diff --git a/typo3/sysext/felogin/Classes/Controller/PasswordRecoveryController.php b/typo3/sysext/felogin/Classes/Controller/PasswordRecoveryController.php
index c89c39b71196d9401cfacad678beb138638c67a7..cacf2ad899d9c177f9bcd91b73d5bdbb7d1526fd 100644
--- a/typo3/sysext/felogin/Classes/Controller/PasswordRecoveryController.php
+++ b/typo3/sysext/felogin/Classes/Controller/PasswordRecoveryController.php
@@ -77,7 +77,7 @@ class PasswordRecoveryController extends AbstractLoginFormController
      * @throws StopActionException
      * @throws \TYPO3\CMS\Extbase\Configuration\Exception\InvalidConfigurationTypeException
      */
-    public function recoveryAction(string $userIdentifier = null)
+    public function recoveryAction(?string $userIdentifier = null)
     {
         if (empty($userIdentifier)) {
             return $this->htmlResponse();