diff --git a/lib/Debug.php b/lib/Debug.php
index f6a8d105..48dbb31a 100644
--- a/lib/Debug.php
+++ b/lib/Debug.php
@@ -7,7 +7,7 @@ class Debug
      */
     public static function isEnabled(): bool
     {
-        $ip = $_SERVER['REMOTE_ADDR'];
+        $ip = $_SERVER['REMOTE_ADDR'] ?? 'x.y.z.1';
         $enableDebugMode = Configuration::getConfig('system', 'enable_debug_mode');
         $debugModeWhitelist = Configuration::getConfig('system', 'debug_mode_whitelist') ?: [];
         if ($enableDebugMode && ($debugModeWhitelist === [] || in_array($ip, $debugModeWhitelist))) {