diff --git a/socket.io-client/socket.io-client.d.ts b/socket.io-client/socket.io-client.d.ts
index 205fb9e9ba..c5d7837641 100644
--- a/socket.io-client/socket.io-client.d.ts
+++ b/socket.io-client/socket.io-client.d.ts
@@ -27,6 +27,7 @@ declare module SocketIOClient {
         emit(event: string, ...args: any[]): Socket;
         listeners(event: string): Function[];
         hasListeners(event: string): boolean;
+        connected: boolean;
     }
 
     interface ManagerStatic {