diff --git a/src/address.js b/src/address.js
index 381515a..aa133c8 100644
--- a/src/address.js
+++ b/src/address.js
@@ -1,48 +1,62 @@
-var base58 = require('./base58');
-var convert = require('./convert');
-var util = require('./util');
-var mainnet = require('./network').mainnet.addressVersion;
+var base58 = require('./base58')
+var convert = require('./convert')
+var error = require('./util').error
+var mainnet = require('./network').mainnet.addressVersion
 
-var Address = function (bytes, version) {
-    if (!(this instanceof Address)) { return new Address(bytes, version); }
-    if (arguments[0] instanceof Address) {
-        this.hash = arguments[0].hash;
-        this.version = arguments[0].version;
-    }
-    else if (typeof bytes === 'string') {
-        this.hash =
-              bytes.length <= 35     ? base58.checkDecode(bytes)
-            : bytes.length <= 40     ? convert.hexToBytes(bytes)
-            :                          util.error('invalid or unrecognized input');
+function Address(bytes, version) {
+  if (!(this instanceof Address))
+    return new Address(bytes, version)
 
-        this.version = version || this.hash.version || mainnet;
-    }
-    else {
-        this.hash = bytes;
-        this.version = version || mainnet;
-    }
-};
+  if (bytes instanceof Address) {
+    this.hash = bytes.hash
+    this.version = bytes.version
+  }
+  else if (typeof bytes === 'string') {
+    this.hash = stringToHash(bytes)
+    this.version = version || this.hash.version || mainnet
+  }
+  else {
+    this.hash = bytes
+    this.version = version || mainnet
+  }
+}
+
+function stringToHash(str) {
+  if (str.length <= 35) {
+    return base58.checkDecode(str)
+  }
+  if (str.length <= 40) {
+    return convert.hexToBytes(str)
+  }
+  error('invalid or unrecognized input')
+}
 
 /**
  * Serialize this object as a standard Bitcoin address.
- *
  * Returns the address as a base58-encoded string in the standardized format.
  */
 Address.prototype.toString = function () {
-    return base58.checkEncode(this.hash.slice(0), this.version);
-};
-
-Address.getVersion = function(string) {
-    return base58.decode(string)[0];
+  return base58.checkEncode(this.hash.slice(0), this.version)
 }
 
-Address.validate = function(string) {
-    try {
-        base58.checkDecode(string);
-        return true;
-    } catch (e) {
-        return false;
-    }
-};
+/**
+ * Returns the version of an address, e.g. if the address belongs to the main
+ * net or the test net.
+ */
+Address.getVersion = function (address) {
+  return base58.decode(address)[0]
+}
 
-module.exports = Address;
+/**
+ * Returns true if a bitcoin address is a valid address, otherwise false.
+ */
+Address.validate = function (address) {
+  try {
+    base58.checkDecode(address)
+    return true
+  } catch (e) {
+    return false
+  }
+}
+
+module.exports = Address
diff --git a/src/hdwallet.js b/src/hdwallet.js
index 8a7dfac..601466f 100644
--- a/src/hdwallet.js
+++ b/src/hdwallet.js
@@ -5,6 +5,7 @@ var format = require('util').format
 var util = require('./util.js')
 var Crypto = require('crypto-js');
 var HmacSHA512 = Crypto.HmacSHA512
+var HMAC= Crypto.algo.HMAC
 var ECKey = require('./eckey.js').ECKey
 var ECPubKey = require('./eckey.js').ECPubKey
 var Address = require('./address.js')
@@ -198,12 +199,12 @@ HDWallet.prototype.derive = function(i) {
         // If 1, private derivation is used:
         // let I = HMAC-SHA512(Key = cpar, Data = 0x00 || kpar || i) [Note:]
         var kPar = this.priv.toBytes().slice(0, 32)
-        I = util.HmacFromBytesToBytes(SHA512, [0].concat(kPar, iBytes), cPar)
+        I = HmacFromBytesToBytes(SHA512, [0].concat(kPar, iBytes), cPar)
     } else {
         // If 0, public derivation is used:
         // let I = HMAC-SHA512(Key = cpar, Data = χ(kpar*G) || i)
         var KPar = this.pub.toBytes(true)
-        I = util.HmacFromBytesToBytes(SHA512, KPar.concat(iBytes), cPar)
+        I = HmacFromBytesToBytes(SHA512, KPar.concat(iBytes), cPar)
     }
 
     // Split I = IL || IR into two 32-byte sequences, IL and IR.
@@ -243,3 +244,9 @@ HDWallet.prototype.getKeyVersion = function() {
 
 HDWallet.prototype.toString = HDWallet.prototype.toBase58
 
+function HmacFromBytesToBytes(hasher, message, key) {
+  var hmac = HMAC.create(hasher, convert.bytesToWordArray(key))
+  hmac.update(convert.bytesToWordArray(message))
+  return convert.wordArrayToBytes(hmac.finalize())
+}
+
diff --git a/src/util.js b/src/util.js
index bdebae8..f33d04d 100644
--- a/src/util.js
+++ b/src/util.js
@@ -1,8 +1,7 @@
 var convert = require('./convert.js')
-var Crypto = require('crypto-js');
-var RIPEMD160 = Crypto.RIPEMD160;
-var SHA256 = Crypto.SHA256;
-var HMAC= Crypto.algo.HMAC;
+var Crypto = require('crypto-js')
+var RIPEMD160 = Crypto.RIPEMD160
+var SHA256 = Crypto.SHA256
 
 /**
  * Calculate RIPEMD160(SHA256(data)).
@@ -11,16 +10,14 @@ var HMAC= Crypto.algo.HMAC;
  * array.
  */
 exports.sha256ripe160 = function (data) {
-    var wordArray = RIPEMD160(SHA256(convert.bytesToWordArray(data)))
-    return convert.wordArrayToBytes(wordArray)
+  var wordArray = RIPEMD160(SHA256(convert.bytesToWordArray(data)))
+  return convert.wordArrayToBytes(wordArray)
 }
 
-exports.HmacFromBytesToBytes = function (hasher, message, key) {
-  var hmac = HMAC.create(hasher, convert.bytesToWordArray(key))
-  hmac.update(convert.bytesToWordArray(message))
-  return convert.wordArrayToBytes(hmac.finalize())
-}
-
-exports.error = function(msg) {
-    throw new Error(msg);
+/**
+ * Convenience method for throw new Error('some message'), e.g.
+ * error('something went wrong')
+ */
+exports.error = function (msg) {
+  throw new Error(msg)
 }