diff --git a/index.php b/index.php
index 9c0eeb5..52b826c 100644
--- a/index.php
+++ b/index.php
@@ -78,7 +78,7 @@ if(php_sapi_name() == 'cli' || $_SERVER["REQUEST_URI"] == '/metrics') {
 
 
             if(!empty($oldconfig) && empty($submetric['value']) && (isset($submetric['fallback']) && !empty($submetric['fallback']))) {
-                if(time() < ($oldconfig[$key]['submetrics'][$subkey]['time'] + $submetric['fallback']['maxage'])) {
+                if(!isset($submetric['fallback']['maxage']) || time() < ($oldconfig[$key]['submetrics'][$subkey]['time'] + $submetric['fallback']['maxage'])) {
                     if($submetric['fallback']['type'] == 'previous') {
                         $submetric['value'] = $oldconfig[$key]['submetrics'][$subkey]['value'];
                     } elseif ($submetric['fallback']['type'] == 'static') {