diff --git a/lib/bootstrap.php b/lib/bootstrap.php
index 20c1be57da9901cf8d8b3d3c6e4457380d6f20e2..8149868019f26b43da544baa5bbf353de35df5dd 100644
--- a/lib/bootstrap.php
+++ b/lib/bootstrap.php
@@ -54,7 +54,7 @@ if (isset($_SERVER['SERVER_NAME'])) {
     $ABSOLUTE_URI_STUDIP .= '://'.$_SERVER['SERVER_NAME'];
 
     if (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on' && $_SERVER['SERVER_PORT'] != 443 ||
-        empty($SERVER['HTTPS']) && $_SERVER['SERVER_PORT'] != 80) {
+        empty($_SERVER['HTTPS']) && $_SERVER['SERVER_PORT'] != 80) {
         $ABSOLUTE_URI_STUDIP .= ':'.$_SERVER['SERVER_PORT'];
     }