diff --git a/src/EventSubscriber/Challenge.php b/src/EventSubscriber/Challenge.php
index d77b8ab..0a6bb9d 100644
--- a/src/EventSubscriber/Challenge.php
+++ b/src/EventSubscriber/Challenge.php
@@ -69,7 +69,7 @@ public function __construct(LoggerChannelFactoryInterface $logger_factory, Flood
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     $events[KernelEvents::REQUEST] = ['protect'];
 
     return $events;