diff --git a/socket.io-client/socket.io-client.d.ts b/socket.io-client/socket.io-client.d.ts
index 7e15773e6d..42d3664128 100644
--- a/socket.io-client/socket.io-client.d.ts
+++ b/socket.io-client/socket.io-client.d.ts
@@ -177,6 +177,12 @@ declare module SocketIOClient {
 		 */
 		nsp: string;
 		
+		/**
+		 * The ID of the socket; matches the server ID and is set when we're connected, and cleared
+		 * when we're disconnected
+		 */
+		id: string;
+		
 		/**
 		 * Are we currently connected?
 		 * @default false