diff --git a/includes/discovery/functions.inc.php b/includes/discovery/functions.inc.php
index 1da9c04668..1dbe76a2ed 100644
--- a/includes/discovery/functions.inc.php
+++ b/includes/discovery/functions.inc.php
@@ -96,7 +96,7 @@ function sensor_low_limit($class, $current)
       $limit = $current * 0.95;
       break;
     case 'current':
-      $limit = 0;
+      $limit = NULL;
       break;
     case 'fanspeed':
       $limit = $current * 0.80;