diff --git a/src/Util/Notification.php b/src/Util/Notification.php
index 63d80fa..928d028 100644
--- a/src/Util/Notification.php
+++ b/src/Util/Notification.php
@@ -50,6 +50,6 @@ public static function verifyNotification(
         $payload = $timestamp . ':' . $request;
         $hash = hash_hmac('sha512', $payload, trim($apiKey));
 
-        return $hash === $sha512hexPayload;
+        return hash_equals($hash, $sha512hexPayload);
     }
 }