diff --git a/src/browser/ReactWithAddons.js b/src/browser/ReactWithAddons.js
index 68b968c8c1..15f242ffee 100644
--- a/src/browser/ReactWithAddons.js
+++ b/src/browser/ReactWithAddons.js
@@ -48,6 +48,7 @@ React.addons = {
 };
 
 if (__DEV__) {
+  React.addons.Perf = require('ReactDefaultPerf');
   React.addons.TestUtils = require('ReactTestUtils');
 }