diff --git a/web/includes/config.php.in b/web/includes/config.php.in
index 12c54906a..bbcf3700d 100644
--- a/web/includes/config.php.in
+++ b/web/includes/config.php.in
@@ -89,6 +89,7 @@ define('ZM_PCRE', '@ZM_PCRE@');                       // PCRE support enabled
 //
 // Alarm states
 //
+define('STATE_UNKNOWN', -1);
 define('STATE_IDLE', 0);
 define('STATE_PREALARM', 1);
 define('STATE_ALARM', 2);