diff --git a/includes/discovery/functions.inc.php b/includes/discovery/functions.inc.php
index c7042b12e3..9d87dcee07 100644
--- a/includes/discovery/functions.inc.php
+++ b/includes/discovery/functions.inc.php
@@ -10,7 +10,7 @@ function discover_sensor(&$valid, $class, $device, $oid, $index, $type, $descr,
     $low_limit = $config['limit']['current'];
   }
   
-  if (mysql_result(mysql_query("SELECT count(sensor_id) FROM `sensors` WHERE sensor_class='humidity' AND device_id = '".$device['device_id']."' AND sensor_type = '$type' AND `sensor_index` = '$index'"),0) == '0')
+  if (mysql_result(mysql_query("SELECT count(sensor_id) FROM `sensors` WHERE sensor_class='" . mres($class) . "' AND device_id = '".$device['device_id']."' AND sensor_type = '$type' AND `sensor_index` = '$index'"),0) == '0')
   {
     $query = "INSERT INTO sensors (`sensor_class`, `device_id`, `sensor_oid`, `sensor_index`, `sensor_type`, `sensor_descr`, `sensor_precision`, `sensor_limit`, `sensor_limit_warn`, `sensor_limit_low`, `sensor_limit_low_warn`, `sensor_current`) ";
     $query .= " VALUES ('" . mres($class) . "', '".$device['device_id']."', '$oid', '$index', '$type', '$descr', '$precision', '$high_limit', '$warn_limit', '$low_limit', '$low_warn_limit', '$current')";