diff --git a/src/Security/Authenticator/OAuth2Authenticator.php b/src/Security/Authenticator/OAuth2Authenticator.php
index 19da045..ffd98d7 100644
--- a/src/Security/Authenticator/OAuth2Authenticator.php
+++ b/src/Security/Authenticator/OAuth2Authenticator.php
@@ -60,7 +60,7 @@ public function supports(Request $request): ?bool
 
     public function start(Request $request, ?AuthenticationException $authException = null): Response
     {
-        return new Response('', 401, ['WWW-Authenticate' => 'Bearer']);
+        return new Response($authException?->getMessage() ?? 'Authentication required', 401, ['WWW-Authenticate' => 'Bearer']);
     }
 
     /**