diff --git a/types/socket.io/index.d.ts b/types/socket.io/index.d.ts
index 6c12e444b0..95a9ff1b4f 100644
--- a/types/socket.io/index.d.ts
+++ b/types/socket.io/index.d.ts
@@ -616,7 +616,7 @@ declare namespace SocketIO {
 		 * take an optional parameter, err, of a possible error
 		 * @return This Socket
 		 */
-		join( name: string, fn?: ( err?: any ) => void ): Socket;
+		join( name: string|string[], fn?: ( err?: any ) => void ): Socket;
 
 		/**
 		 * Leaves a room