diff --git a/lib/cloneDeep.js b/lib/cloneDeep.js
index 90a0299..e09e979 100644
--- a/lib/cloneDeep.js
+++ b/lib/cloneDeep.js
@@ -1,17 +1,15 @@
+var isA = require('./isA');
+
 module.exports = function cloneDeep(o) {
-    var newO,
-        i;
+    var newO;
 
-    if (typeof o !== 'object') {
-        return o;
-    }
-    if (!o) {
+    if (!o || typeof o !== 'object') {
         return o;
     }
 
-    if ('[object Array]' === Object.prototype.toString.apply(o)) {
+    if (isA(o, Array)) {
         newO = [];
-        for (i = 0; i < o.length; i += 1) {
+        for (var i = 0, j = o.length; i < j; i += 1) {
             newO[i] = cloneDeep(o[i]);
         }
         return newO;