diff --git a/src/index.tsx b/src/index.tsx
index 76f05cc..4725bab 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -3,6 +3,7 @@ import index from "./index.html";
 import { getMatchInfo, listEvent } from "./utils";
 
 const server = serve({
+  port: process.env.PORT || 3000,
   routes: {
     // Serve index.html for all unmatched routes.
     "/*": index,