diff --git a/src/StripeWebhooksController.php b/src/StripeWebhooksController.php
index ac757d6..4475b13 100644
--- a/src/StripeWebhooksController.php
+++ b/src/StripeWebhooksController.php
@@ -8,7 +8,7 @@
 
 class StripeWebhooksController
 {
-    public function __invoke(Request $request, string $configKey = null)
+    public function __invoke(Request $request, string|null $configKey = null)
     {
         $webhookConfig = new WebhookConfig([
             'name' => 'stripe',