diff --git a/index.js b/index.js
index 37ec9d7..d77f0fd 100644
--- a/index.js
+++ b/index.js
@@ -29,6 +29,8 @@ export default {
 
     if (method === 'OPTIONS') return new Response(null, { status: 204, headers: CORS_HEADERS });
 
+    if ((h => h !== 'sune.planetrenox.com' && !h.endsWith('.github.io'))(new URL(req.headers.get('Origin') || 'null').hostname)) return withCORS(new Response('Forbidden', { status: 403 }));
+
     if (url.pathname === '/ws') {
       const isGet = method === 'GET';
       const isWs = req.headers.get('Upgrade') === 'websocket';