diff --git a/index.php b/index.php
index 1b33749..08a2c3e 100644
--- a/index.php
+++ b/index.php
@@ -7,6 +7,9 @@ if (isset($_SESSION['Firma']['ID']))
 	define('GUELTIG', $_SESSION['Firma']['A_Bis']);
 	define('ZAHLBAR', $_SESSION['Firma']['Z_Bis']);
 }
+if (!defined('PREFIX')) {
+	define('PREFIX', '');
+}
 if ('Test' == PREFIX)
 {
 	exit();