diff --git a/lib/hdprivatekey.js b/lib/hdprivatekey.js
index 230dc03..989a723 100644
--- a/lib/hdprivatekey.js
+++ b/lib/hdprivatekey.js
@@ -4,6 +4,7 @@
 var assert = require('assert');
 var buffer = require('buffer');
 var _ = require('lodash');
+var $ = require('./util/preconditions');
 
 var BN = require('./crypto/bn');
 var Base58 = require('./encoding/base58');
@@ -277,7 +278,18 @@ HDPrivateKey._validateNetwork = function(data, networkArg) {
   return null;
 };
 
-HDPrivateKey.fromJSON = HDPrivateKey.fromObject = HDPrivateKey.fromString = function(arg) {
+HDPrivateKey.fromJSON = function(arg) {
+  $.checkArgument(JSUtil.isValidJSON(arg), 'No valid JSON string was provided');
+  return new HDPrivateKey(arg);
+};
+
+HDPrivateKey.fromString = function(arg) {
+  $.checkArgument(_.isString(arg), 'No valid string was provided');
+  return new HDPrivateKey(arg);
+};
+
+HDPrivateKey.fromObject = function(arg) {
+  $.checkArgument(_.isObject(arg), 'No valid argument was provided');
   return new HDPrivateKey(arg);
 };
 
diff --git a/lib/hdpublickey.js b/lib/hdpublickey.js
index 2a85048..e23774a 100644
--- a/lib/hdpublickey.js
+++ b/lib/hdpublickey.js
@@ -1,6 +1,8 @@
 'use strict';
 
 var _ = require('lodash');
+var $ = require('./util/preconditions');
+
 var BN = require('./crypto/bn');
 var Base58 = require('./encoding/base58');
 var Base58Check = require('./encoding/base58check');
@@ -356,7 +358,18 @@ HDPublicKey._validateBufferArguments = function (arg) {
   }
 };
 
-HDPublicKey.fromString = HDPublicKey.fromObject = HDPublicKey.fromJSON = function(arg) {
+HDPublicKey.fromJSON = function(arg) {
+  $.checkArgument(JSUtil.isValidJSON(arg), 'No valid JSON string was provided');
+  return new HDPublicKey(arg);
+};
+
+HDPublicKey.fromObject = function(arg) {
+  $.checkArgument(_.isObject(arg), 'No valid argument was provided');
+  return new HDPublicKey(arg);
+};
+
+HDPublicKey.fromString = function(arg) {
+  $.checkArgument(_.isString(arg), 'No valid string was provided');
   return new HDPublicKey(arg);
 };
 
diff --git a/lib/util/js.js b/lib/util/js.js
index 9366510..be6f366 100644
--- a/lib/util/js.js
+++ b/lib/util/js.js
@@ -29,6 +29,9 @@ module.exports = {
    */
   isValidJSON: function isValidJSON(arg) {
     var parsed;
+    if (!_.isString(arg)) {
+      return false;
+    }
     try {
       parsed = JSON.parse(arg);
     } catch (e) {
diff --git a/test/hdkeys.js b/test/hdkeys.js
index d941eda..36900a0 100644
--- a/test/hdkeys.js
+++ b/test/hdkeys.js
@@ -10,12 +10,48 @@
 /* jshint maxstatements: 100 */
 /* jshint unused: false */
 
+var _ = require('lodash');
 var should = require('chai').should();
+var expect = require('chai').expect;
 var bitcore = require('..');
 var Networks = bitcore.Networks;
 var HDPrivateKey = bitcore.HDPrivateKey;
 var HDPublicKey = bitcore.HDPublicKey;
 
+describe('HDKeys building with static methods', function() {
+  var classes = [HDPublicKey, HDPrivateKey];
+  var clazz, index;
+
+  _.each(classes, function(clazz) {
+    var expectStaticMethodFail = function(staticMethod, argument, message) {
+      expect(clazz[staticMethod].bind(null, argument)).to.throw(message);
+    };
+    it(clazz.name + ' fromJSON checks that a valid JSON is provided', function() {
+      var errorMessage = 'No valid JSON string was provided';
+      var method = 'fromJSON';
+      expectStaticMethodFail(method, undefined, errorMessage);
+      expectStaticMethodFail(method, null, errorMessage);
+      expectStaticMethodFail(method, 'invalid JSON', errorMessage);
+      expectStaticMethodFail(method, '{\'singlequotes\': true}', errorMessage);
+      expectStaticMethodFail(method, {}, errorMessage);
+    });
+    it(clazz.name + ' fromString checks that a string is provided', function() {
+      var errorMessage = 'No valid string was provided';
+      var method = 'fromString';
+      expectStaticMethodFail(method, undefined, errorMessage);
+      expectStaticMethodFail(method, null, errorMessage);
+      expectStaticMethodFail(method, {}, errorMessage);
+    });
+    it(clazz.name + ' fromObject checks that an object is provided', function() {
+      var errorMessage = 'No valid argument was provided';
+      var method = 'fromObject';
+      expectStaticMethodFail(method, undefined, errorMessage);
+      expectStaticMethodFail(method, null, errorMessage);
+      expectStaticMethodFail(method, '', errorMessage);
+    });
+  });
+});
+
 describe('BIP32 compliance', function() {
 
   it('should initialize test vector 1 from the extended public key', function() {
diff --git a/test/hdprivatekey.js b/test/hdprivatekey.js
index 665eb37..b41ab9f 100644
--- a/test/hdprivatekey.js
+++ b/test/hdprivatekey.js
@@ -78,14 +78,13 @@ describe('HDPrivate key interface', function() {
     ));
   });
 
-  describe('should error with a nonsensical argument', function() {
-    it('like a number', function() {
+  describe('instantiation', function() {
+    it('invalid argument: can not instantiate from a number', function() {
       expectFailBuilding(1, hdErrors.UnrecognizedArgument);
     });
-  });
-
-  it('allows no-new calling', function() {
-    HDPrivateKey(xprivkey).toString().should.equal(xprivkey);
+    it('allows no-new calling', function() {
+      HDPrivateKey(xprivkey).toString().should.equal(xprivkey);
+    });
   });
 
   it('inspect() displays correctly', function() {
diff --git a/test/hdpublickey.js b/test/hdpublickey.js
index df4faf5..c0e4938 100644
--- a/test/hdpublickey.js
+++ b/test/hdpublickey.js
@@ -122,7 +122,6 @@ describe('HDPublicKey interface', function() {
         return new HDPublicKey(buffers);
       }, errors.InvalidB58Checksum);
     });
-
   });
 
   describe('error checking on serialization', function() {
@@ -246,7 +245,7 @@ describe('HDPublicKey interface', function() {
 
   it('rejects illegal paths', function() {
     var valid;
-    
+
     valid = HDPublicKey.isValidPath('m/-1/12');
     valid.should.equal(false);