diff --git a/lib/util/js.js b/lib/util/js.js
index 05c9562..9366510 100644
--- a/lib/util/js.js
+++ b/lib/util/js.js
@@ -28,11 +28,16 @@ module.exports = {
    * @return {Object|boolean} false if the argument is not a JSON string.
    */
   isValidJSON: function isValidJSON(arg) {
+    var parsed;
     try {
-      return JSON.parse(arg);
+      parsed = JSON.parse(arg);
     } catch (e) {
       return false;
     }
+    if (typeof(parsed) === 'object') {
+      return true;
+    }
+    return false;
   },
   isHexa: isHexa,
   isHexaString: isHexa,
diff --git a/test/privatekey.js b/test/privatekey.js
index 7cae44b..dcaab92 100644
--- a/test/privatekey.js
+++ b/test/privatekey.js
@@ -16,6 +16,7 @@ var invalidbase58 = require('./data/bitcoind/base58_keys_invalid.json');
 
 describe('PrivateKey', function() {
   var hex = '96c132224121b509b7d0a16245e957d9192609c5637c6228311287b1be21627a';
+  var hex2 = '8080808080808080808080808080808080808080808080808080808080808080';
   var buf = new Buffer(hex, 'hex');
   var wifTestnet = 'cSdkPxkAjA4HDr5VHgsebAPDEh9Gyub4HK8UJr2DFGGqKKy4K5sG';
   var wifTestnetUncompressed = '92jJzK4tbURm1C7udQXxeCBvXHoHJstDXRxAMouPG1k1XUaXdsu';
@@ -31,6 +32,12 @@ describe('PrivateKey', function() {
     should.exist(b.bn);
   });
 
+  it('should create a privatekey from hexa string', function() {
+    var a = new PrivateKey(hex2);
+    should.exist(a);
+    should.exist(a.bn);
+  });
+
   it('should create a new random testnet private key with only one argument', function() {
     var a = new PrivateKey(Networks.testnet);
     should.exist(a);
diff --git a/test/util/js.js b/test/util/js.js
new file mode 100644
index 0000000..b392300
--- /dev/null
+++ b/test/util/js.js
@@ -0,0 +1,35 @@
+'use strict';
+/* jshint unused: false */
+
+var should = require('chai').should();
+var expect = require('chai').expect;
+
+var bitcore = require('../..');
+var JSUtil = bitcore.util.js;
+
+describe('js utils', function() {
+
+  describe('isValidJSON', function() {
+    
+    var hexa = '8080808080808080808080808080808080808080808080808080808080808080';
+    var json = '{"key": ["value", "value2"]}';
+    var json2 = '["value", "value2", {"key": "value"}]';
+
+    it('does not mistake an integer as valid json object', function() {
+      var valid = JSUtil.isValidJSON(hexa);
+      valid.should.equal(false);
+    });
+
+    it('correctly validates a json object', function() {
+      var valid = JSUtil.isValidJSON(json);
+      valid.should.equal(true);
+    });
+
+    it('correctly validates an array json object', function() {
+      var valid = JSUtil.isValidJSON(json);
+      valid.should.equal(true);
+    });
+
+  });
+
+});