Index: init.php
--- init.php.orig
+++ init.php
@@ -9,4 +9,6 @@
 
 	// Defines the base path on the server, terminated by a slash
 	define('BASE_PATH', realpath(dirname(__FILE__)) . '/');
-	define('UMAPI_PATH', '/usr/share/php-mapi');
+
+	define('GROOT', realpath(implode(DIRECTORY_SEPARATOR, [__DIR__, '..'])));
+	define('UMAPI_PATH', GROOT . DIRECTORY_SEPARATOR . 'grommunio-mapi-header-php');