diff --git a/src/utils/shallowEqual.js b/src/utils/shallowEqual.js
index d8946ac02e..78d4848b9a 100644
--- a/src/utils/shallowEqual.js
+++ b/src/utils/shallowEqual.js
@@ -23,20 +23,21 @@ function shallowEqual(objA, objB) {
     return true;
   }
 
-  if (typeof objA !== 'object' || objA === null
-      || typeof objB !== 'object' || objB === null) {
+  if (typeof objA !== 'object' || objA === null ||
+      typeof objB !== 'object' || objB === null) {
     return false;
   }
 
-  var keysA = Object.keys(objA), keysB = Object.keys(objB);
+  var keysA = Object.keys(objA);
+  var keysB = Object.keys(objB);
 
   if (keysA.length !== keysB.length) {
     return false;
   }
 
   // Test for A's keys different from B.
-  var bHasOwnProperty = objB.hasOwnProperty.bind(objB);
-  for (var i = 0, length = keysA.length; i < length; i++) {
+  var bHasOwnProperty = Object.prototype.hasOwnProperty.bind(objB);
+  for (var i = 0; i < keysA.length; i++) {
     if (!bHasOwnProperty(keysA[i]) || objA[keysA[i]] !== objB[keysA[i]]) {
       return false;
     }