diff --git a/src/DrupalEnvDetector.php b/src/DrupalEnvDetector.php
index d08231f..eb45275 100644
--- a/src/DrupalEnvDetector.php
+++ b/src/DrupalEnvDetector.php
@@ -55,7 +55,7 @@ public function __construct($settings_dir) {
     }
 
     // Set reverse proxy
-    if (isset($_SERVER['REMOTE_ADDR'])) {
+    if (isset($_SERVER['REMOTE_ADDR']) && isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
       if ($_SERVER['REMOTE_ADDR'] !== $_SERVER['HTTP_X_FORWARDED_FOR']) {
         $settings['reverse_proxy'] = TRUE;
         $settings['reverse_proxy_addresses'] = [$_SERVER['REMOTE_ADDR']];