diff --git a/socket.io-client/index.d.ts b/socket.io-client/index.d.ts
index 9bc6e1185c..f4aef879a8 100644
--- a/socket.io-client/index.d.ts
+++ b/socket.io-client/index.d.ts
@@ -410,7 +410,7 @@ declare namespace SocketIOClient {
 		 * @param The connection timeout milliseconds
 		 * @return This Manager
 		 */
-		timeout(v: boolean): Manager;
+		timeout(v: number): Manager;
 
 		/**
 		 * Sets the current transport socket and opens our connection