diff --git a/index.js b/index.js
index 9762d26..0523485 100644
--- a/index.js
+++ b/index.js
@@ -27,7 +27,8 @@ module.exports = function main (
   for (const f of fs.readdirSync (modulefolder)) {
     const regex = /(?<method>.*?)-(?<url>.*?)\.js/u;
     const { groups } = regex.exec (f);
-    groups.url = `/${subdir}/${groups.url}/`;
+    if ('undefined' !== typeof subdir)
+      groups.url = `/${subdir}/${groups.url}/`;
     groups.url = groups.url
       .replace (/^\/[^/]*\/root/iu, '/')
       .replace (/\./gu, '/')