diff --git a/test/core/fixtures/transformation/es7.decorators/class/expected.js b/test/core/fixtures/transformation/es7.decorators/class/expected.js
index 02b4a68b90..96ff2b4054 100644
--- a/test/core/fixtures/transformation/es7.decorators/class/expected.js
+++ b/test/core/fixtures/transformation/es7.decorators/class/expected.js
@@ -1,3 +1,4 @@
+"use strict";
 
 var Foo = (function () {
   function Foo() {