diff --git a/Tests/phpt/autoload.php b/Tests/phpt/autoload.php
index 154b3ab..6e5bd09 100644
--- a/Tests/phpt/autoload.php
+++ b/Tests/phpt/autoload.php
@@ -11,7 +11,7 @@
 
 use Symfony\Component\Runtime\SymfonyRuntime;
 
-$_SERVER['APP_RUNTIME_OPTIONS'] = $_SERVER['APP_RUNTIME_OPTIONS'] ?? [];
+$_SERVER['APP_RUNTIME_OPTIONS'] ??= [];
 $_SERVER['APP_RUNTIME_OPTIONS'] += [
     'project_dir' => __DIR__,
 ] + ($_SERVER['APP_RUNTIME_OPTIONS'] ?? []);