diff --git a/Libraries/Utilities/deepFreezeAndThrowOnMutationInDev.js b/Libraries/Utilities/deepFreezeAndThrowOnMutationInDev.js
index b1dac7777..9ab2cc4b1 100644
--- a/Libraries/Utilities/deepFreezeAndThrowOnMutationInDev.js
+++ b/Libraries/Utilities/deepFreezeAndThrowOnMutationInDev.js
@@ -38,7 +38,10 @@ function deepFreezeAndThrowOnMutationInDev(object: Object) {
       return;
     }
 
-    for (var key in object) {
+    var keys = Object.keys(object);
+
+    for (var i = 0; i < keys.length; i++) {
+      var key = keys[i];
       if (object.hasOwnProperty(key)) {
         object.__defineGetter__(key, identity.bind(null, object[key]));
         object.__defineSetter__(key, throwOnImmutableMutation.bind(null, key));
@@ -48,7 +51,8 @@ function deepFreezeAndThrowOnMutationInDev(object: Object) {
     Object.freeze(object);
     Object.seal(object);
 
-    for (var key in object) {
+    for (var i = 0; i < keys.length; i++) {
+      var key = keys[i];
       if (object.hasOwnProperty(key)) {
         deepFreezeAndThrowOnMutationInDev(object[key]);
       }