diff --git a/js/models/core/PublicKeyRing.js b/js/models/core/PublicKeyRing.js
index f8a090d10..e05fa8049 100644
--- a/js/models/core/PublicKeyRing.js
+++ b/js/models/core/PublicKeyRing.js
@@ -190,7 +190,7 @@ PublicKeyRing.prototype.getScriptPubKeyHex = function(index, isChange) {
 
 //generate a new address, update index.
 PublicKeyRing.prototype.generateAddress = function(isChange) {
-
+  isChange = !!isChange;
   var index = isChange ? this.indexes.getChangeIndex() : this.indexes.getReceiveIndex();
   var ret = this.getAddress(index, isChange);
   this.indexes.increment(isChange);
diff --git a/js/models/core/Structure.js b/js/models/core/Structure.js
index f6c160568..88543f966 100644
--- a/js/models/core/Structure.js
+++ b/js/models/core/Structure.js
@@ -1,6 +1,7 @@
 'use strict';
 
 var imports = require('soop').imports();
+var preconditions = require('preconditions').singleton();
 
 function Structure() {}
 
@@ -18,6 +19,8 @@ var BIP45_PUBLIC_PREFIX = 'm/' + PURPOSE + '\'';
 Structure.BIP45_PUBLIC_PREFIX = BIP45_PUBLIC_PREFIX;
 
 Structure.Branch = function(address_index, isChange, cosigner_index) {
+  preconditions.shouldBeNumber(address_index);
+  preconditions.shouldBeBoolean(isChange);
   var ret = 'm/' +
     (typeof cosigner_index !== 'undefined' ? cosigner_index : SHARED_INDEX) + '/' +
     (isChange ? 1 : 0) + '/' +
@@ -32,6 +35,7 @@ Structure.FullBranch = function(address_index, isChange, cosigner_index) {
 };
 
 Structure.indicesForPath = function(path) {
+  preconditions.shouldBeString(path);
   var s = path.split('/');
   return {
     isChange: s[3] === '1',
@@ -39,8 +43,8 @@ Structure.indicesForPath = function(path) {
   };
 };
 
-Structure.IdFullBranch = Structure.FullBranch(0, 0, ID_INDEX);
-Structure.IdBranch = Structure.Branch(0, 0, ID_INDEX);
+Structure.IdFullBranch = Structure.FullBranch(0, false, ID_INDEX);
+Structure.IdBranch = Structure.Branch(0, false, ID_INDEX);
 Structure.PURPOSE = PURPOSE;
 Structure.MAX_NON_HARDENED = MAX_NON_HARDENED;
 Structure.SHARED_INDEX = SHARED_INDEX;
diff --git a/js/models/core/Wallet.js b/js/models/core/Wallet.js
index 66c91c54f..9f0da8c2f 100644
--- a/js/models/core/Wallet.js
+++ b/js/models/core/Wallet.js
@@ -5,7 +5,7 @@ var imports = require('soop').imports();
 var http = require('http');
 var EventEmitter = imports.EventEmitter || require('events').EventEmitter;
 var async = require('async');
-var preconditions = require('preconditions').instance();
+var preconditions = require('preconditions').singleton();
 
 var bitcore = require('bitcore');
 var bignum = bitcore.Bignum;
diff --git a/test/test.PrivateKey.js b/test/test.PrivateKey.js
index e5751e699..60ca71664 100644
--- a/test/test.PrivateKey.js
+++ b/test/test.PrivateKey.js
@@ -33,7 +33,7 @@ describe('PrivateKey model', function() {
 
   it('should derive priv keys', function() {
     var pk = new PrivateKey(config);
-    for (var j = 0; j < 2; j++) {
+    for (var j = false; !j; j=true) {
       for (var i = 0; i < 3; i++) {
         var wk = pk.get(i, j);
         should.exist(wk);
@@ -78,10 +78,10 @@ describe('PrivateKey model', function() {
     w2.toObj().extendedPrivateKeyString.should.equal(w1.toObj().extendedPrivateKeyString);
     w2.getId().should.equal(w1.getId());
 
-    JSON.stringify(w2.get(1, 1).storeObj()).should
-      .equal(JSON.stringify(w1.get(1, 1).storeObj()));
-    JSON.stringify(w2.get(1, 0).storeObj()).should
-      .equal(JSON.stringify(w1.get(1, 0).storeObj()));
+    JSON.stringify(w2.get(1, true).storeObj()).should
+      .equal(JSON.stringify(w1.get(1, true).storeObj()));
+    JSON.stringify(w2.get(1, false).storeObj()).should
+      .equal(JSON.stringify(w1.get(1, false).storeObj()));
   });
 
   describe('#getId', function() {
diff --git a/test/test.PublicKeyRing.js b/test/test.PublicKeyRing.js
index 7ffa29691..b2405a161 100644
--- a/test/test.PublicKeyRing.js
+++ b/test/test.PublicKeyRing.js
@@ -121,7 +121,7 @@ describe('PublicKeyRing model', function() {
     var k = createW();
     var w = k.w;
 
-    for (var isChange = 0; isChange < 2; isChange++) {
+    [true, false].forEach(function(isChange){
       for (var i = 0; i < 2; i++) {
         var a = w.generateAddress(isChange);
         a.isValid().should.equal(true);
@@ -132,7 +132,7 @@ describe('PublicKeyRing model', function() {
             .not.equal(w.getAddress(i - 2, isChange).toString());
         }
       }
-    }
+    });
   });
 
   it('should return PublicKeyRing addresses', function() {
@@ -143,9 +143,11 @@ describe('PublicKeyRing model', function() {
     var a = w.getAddresses();
     a.length.should.equal(0);
 
-    for (var isChange = 0; isChange < 2; isChange++)
-      for (var i = 0; i < 2; i++)
+    [true, false].forEach(function(isChange){
+      for (var i = 0; i < 2; i++) {
         w.generateAddress(isChange);
+      }
+    });
 
     var as = w.getAddressesInfo();
     as.length.should.equal(4);
diff --git a/test/test.TxProposals.js b/test/test.TxProposals.js
index c78ef4100..30615a990 100644
--- a/test/test.TxProposals.js
+++ b/test/test.TxProposals.js
@@ -69,14 +69,15 @@ var vopts = {
 
 describe('TxProposals model', function() {
 
+  var isChange = false;
+  var index = 0;
+
   it('verify TXs', function(done) {
 
     var priv = new PrivateKey(config);
     var priv2 = new PrivateKey(config);
     var priv3 = new PrivateKey(config);
     var ts = Date.now();
-    var isChange = 0;
-    var index = 0;
     var pkr = createPKR([priv, priv2, priv3]);
     var opts = {
       remainderOut: {
@@ -186,8 +187,6 @@ describe('TxProposals model', function() {
     var start = new Date().getTime();
     var pkr = createPKR([priv]);
     var ts = Date.now();
-    var isChange = 0;
-    var index = 0;
     unspentTest[0].address = pkr.getAddress(index, isChange).toString();
     unspentTest[0].scriptPubKey = pkr.getScriptPubKeyHex(index, isChange);
     w.add(createTx(
@@ -211,8 +210,6 @@ describe('TxProposals model', function() {
     var start = new Date().getTime();
     var pkr = createPKR([priv]);
     var ts = Date.now();
-    var isChange = 0;
-    var index = 0;
 
     unspentTest[0].address = pkr.getAddress(index, isChange).toString();
     unspentTest[0].scriptPubKey = pkr.getScriptPubKeyHex(index, isChange);
@@ -250,8 +247,6 @@ describe('TxProposals model', function() {
     var priv2 = new PrivateKey(config);
     var priv = new PrivateKey(config);
     var ts = Date.now();
-    var isChange = 0;
-    var index = 0;
     var pkr = createPKR([priv]);
     var opts = {
       remainderOut: {
@@ -353,8 +348,6 @@ describe('TxProposals model', function() {
     var priv3 = PrivateKey.fromObj(o3);
 
     var ts = Date.now();
-    var isChange = 0;
-    var index = 0;
     var pkr = createPKR([priv, priv2]);
     var opts = {
       remainderOut: {
@@ -467,8 +460,6 @@ describe('TxProposals model', function() {
     var priv2 = new PrivateKey(config);
     var priv3 = new PrivateKey(config);
     var ts = Date.now();
-    var isChange = 0;
-    var index = 0;
     var pkr = createPKR([priv, priv2, priv3]);
     var opts = {
       remainderOut: {
@@ -573,8 +564,6 @@ describe('TxProposals model', function() {
       networkName: config.networkName,
     });
     var ts = Date.now();
-    var isChange = 0;
-    var index = 0;
 
     unspentTest[0].address = pkr.getAddress(index, isChange).toString();
     unspentTest[0].scriptPubKey = pkr.getScriptPubKeyHex(index, isChange);