diff --git a/types/simple-mock/index.d.ts b/types/simple-mock/index.d.ts
index fa934dd00f..06c170ebaf 100644
--- a/types/simple-mock/index.d.ts
+++ b/types/simple-mock/index.d.ts
@@ -2,6 +2,7 @@
 // Project: https://github.com/jupiter/simple-mock
 // Definitions by: Leon Yu <https://github.com/leonyu>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.2
 
 declare namespace Simple {
   type Fn<T> = {