diff --git a/src/Dispatcher.js b/src/Dispatcher.js
index bafbc3449cd04d..fb7650655bbe58 100644
--- a/src/Dispatcher.js
+++ b/src/Dispatcher.js
@@ -10,6 +10,8 @@
  * @typechecks
  */
 
+"use strict";
+
 var invariant = require('./invariant');
 
 var _lastID = 1;