diff --git a/Security/ShibbolethAuthenticator.php b/Security/ShibbolethAuthenticator.php
index cdb37ef..06b19b9 100644
--- a/Security/ShibbolethAuthenticator.php
+++ b/Security/ShibbolethAuthenticator.php
@@ -153,7 +153,7 @@ public function checkCredentials($credentials, UserInterface $user)
      *
      * @return RedirectResponse|void
      */
-    public function onAuthenticationSuccess(Request $request, TokenInterface $token, string $providerKey)
+    public function onAuthenticationSuccess(Request $request, TokenInterface $token, $providerKey)
     {
         $this->logger->debug('[ShibbolethAuthenticator::onAuthenticationSuccess]');