diff --git a/public/install.php b/public/install.php
index 52f4bf01a52bc9646ac659304b33e12b769590ab..6d719699c9538dae137752e4f8378a96ea13f995 100644
--- a/public/install.php
+++ b/public/install.php
@@ -29,6 +29,7 @@ require_once 'lib/classes/LinkButton.class.php';
 require_once 'lib/classes/StudipInstaller.php';
 require_once 'lib/classes/SystemChecker.php';
 require_once 'lib/classes/Markup.class.php';
+require_once 'lib/exceptions/AccessDeniedException.php';
 require_once 'vendor/phpass/PasswordHash.php';
 
 // Mock gettext functions if extension is not available