diff --git a/public/portal/index.php b/public/portal/index.php
index 4130970363..cce9cf86c9 100644
--- a/public/portal/index.php
+++ b/public/portal/index.php
@@ -43,6 +43,8 @@ if (!$app->isInstalled()) {
     exit;
 }
 
+$basePath = null;
+
 if (Url::detectIsInPortalDir()) {
     $basePath = '../';