diff --git a/types/sharedworker/index.d.ts b/types/sharedworker/index.d.ts
index 8cd19d6b68..9614fa98ef 100644
--- a/types/sharedworker/index.d.ts
+++ b/types/sharedworker/index.d.ts
@@ -2,6 +2,8 @@
 // Project: http://www.w3.org/TR/workers/
 // Definitions by: Toshiya Nakakura <https://github.com/nakakura>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.8
+
 declare namespace SharedWorker {
     interface AbstractWorker extends EventTarget {
         onerror: (ev: ErrorEvent) => any;