diff --git a/index.php b/index.php
index e9af83f1..83a9a9d7 100644
--- a/index.php
+++ b/index.php
@@ -4,7 +4,7 @@
 
 require_once __DIR__ . '/flight/autoload.php';
 
-Flight::route('/', function () {
+Flight::route('/', static function (): void {
     echo 'hello world!';
 });