diff --git a/src/BrowserKitDriver.php b/src/BrowserKitDriver.php
index 2036124..0c9b921 100644
--- a/src/BrowserKitDriver.php
+++ b/src/BrowserKitDriver.php
@@ -55,7 +55,7 @@ public function __construct(AbstractBrowser $client, $baseUrl = null)
         $this->client->followRedirects(true);
 
         if ($baseUrl !== null && $client instanceof HttpKernelBrowser) {
-            $client->setServerParameter('SCRIPT_FILENAME', parse_url($baseUrl, PHP_URL_PATH));
+            $client->setServerParameter('SCRIPT_FILENAME', parse_url($baseUrl, PHP_URL_PATH) ?? '');
         }
     }