diff --git a/types/express-promise-router/index.d.ts b/types/express-promise-router/index.d.ts
index 08b0ac13f9..507f6d0e40 100644
--- a/types/express-promise-router/index.d.ts
+++ b/types/express-promise-router/index.d.ts
@@ -2,6 +2,7 @@
 // Project: https://github.com/express-promise-router/express-promise-router
 // Definitions by: Anjun Wang <https://github.com/wanganjun>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.3
 
 /* =================== USAGE ===================
 import Router = require('express-promise-router');