diff --git a/src/index.ts b/src/index.ts
index 1e408ee..9b2978f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,5 +1,10 @@
 import { decode } from "./protocol";
-import { type Client, getOrCreateSession, getSession } from "./session";
+import {
+  type Client,
+  type WsData,
+  getOrCreateSession,
+  getSession,
+} from "./session";
 
 const PORT = Number(process.env.PORT) || 4040;
 
@@ -9,7 +14,7 @@ function isValidRoomName(name: unknown): name is string {
   return /^[a-zA-Z0-9_-]+$/.test(name);
 }
 
-Bun.serve({
+Bun.serve<WsData>({
   port: PORT,
   fetch(req, server) {
     const url = new URL(req.url);
diff --git a/src/session.ts b/src/session.ts
index 6b316eb..b68b8e0 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -2,8 +2,13 @@ import type { ServerWebSocket } from "bun";
 import * as Y from "yjs";
 import { encode } from "./protocol";
 
+export interface WsData {
+  room: string | null;
+  client: Client | null;
+}
+
 export interface Client {
-  ws: ServerWebSocket<{ room: string | null }>;
+  ws: ServerWebSocket<WsData>;
 }
 
 export class Session {