diff --git a/tileserver.php b/tileserver.php
index 68d27e5..877030a 100644
--- a/tileserver.php
+++ b/tileserver.php
@@ -1228,7 +1228,7 @@ class Router {
     $request_method = strtolower($_SERVER['REQUEST_METHOD']);
     $path_info = '/';
 	global $config;
-	$config['protocol'] = ((isset($_SERVER['HTTPS']) or $_SERVER['SERVER_PORT'] == '443') or $_SERVER['X-Forwarded-Proto']) == 'https' ? 'https' : 'http';
+	$config['protocol'] = ((isset($_SERVER['HTTPS']) or $_SERVER['SERVER_PORT'] == '443') or $_SERVER['HTTP_X_FORWARDED_PROTO']) == 'https' ? 'https' : 'http';
     if (!empty($_SERVER['PATH_INFO'])) {
       $path_info = $_SERVER['PATH_INFO'];
     } else if (!empty($_SERVER['ORIG_PATH_INFO']) && strpos($_SERVER['ORIG_PATH_INFO'], 'tileserver.php') === false) {