diff --git a/src/server.tsx b/src/server.tsx
index 520665f..6037761 100644
--- a/src/server.tsx
+++ b/src/server.tsx
@@ -30,13 +30,16 @@ const app = new Hono
 
 app.get("/tunnel", c => {
     const app = c.req.query("app")
-    if (!app) {
+    if (!app)
         return c.text("need ?app name", 502)
-    }
+
+    const subdomain = c.req.query("subdomain") || ""
+    if (subdomain && connections[subdomain])
+        return c.text("subdomain taken", 502)
 
     return upgradeWebSocket(c, {
         async onOpen(_event, ws) {
-            const name = randomName()
+            const name = subdomain || randomName()
             connections[name] = { app, ws }
             console.log(`connection opened: ${name} -> ${app}`)
             send(ws, { subdomain: name })