diff --git a/includes/polling/functions.inc.php b/includes/polling/functions.inc.php
index bb6ef9cc14..796d738519 100644
--- a/includes/polling/functions.inc.php
+++ b/includes/polling/functions.inc.php
@@ -1,6 +1,6 @@
 <?php
 
-require_once 'includes/device-groups.inc.php';
+require_once $config['install_dir'].'/includes/device-groups.inc.php';
 
 function poll_sensor($device, $class, $unit) {
     global $config, $memcache, $agent_sensors;