diff --git a/node-zookeeper-client/index.d.ts b/node-zookeeper-client/index.d.ts
index f405aeffc7..cb9979e9f4 100644
--- a/node-zookeeper-client/index.d.ts
+++ b/node-zookeeper-client/index.d.ts
@@ -2,6 +2,7 @@
 // Project: https://github.com/alexguan/node-zookeeper-client
 // Definitions by: York Yao <https://github.com/plantain-00/>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.1
 
 /// <reference types="node" />