diff --git a/lib/dn.js b/lib/dn.js
index d41df44..b03ce15 100644
--- a/lib/dn.js
+++ b/lib/dn.js
@@ -1,6 +1,10 @@
 // Copyright 2011 Mark Cavage, Inc.  All rights reserved.
 
 
+var assert = require('assert-plus');
+
+
+///--- Helpers
 
 function invalidDN(name) {
   var e = new Error();
@@ -9,18 +13,26 @@ function invalidDN(name) {
   return e;
 }
 
-
 function isAlphaNumeric(c) {
   var re = /[A-Za-z0-9]/;
   return re.test(c);
 }
 
-
 function isWhitespace(c) {
   var re = /\s/;
   return re.test(c);
 }
 
+function repeatChar(c, n) {
+  var out = '';
+  var max = n ? n : 0;
+  for (var i = 0; i < max; i++)
+    out += c;
+  return out;
+}
+
+///--- API
+
 function RDN(obj) {
   var self = this;
   this.attrs = {};
@@ -32,12 +44,10 @@ function RDN(obj) {
   }
 }
 
+RDN.prototype.set = function rdnSet(name, value, opts) {
+  assert.string(name, 'name (string) required');
+  assert.string(value, 'value (string) required');
 
-RDN.prototype.set = function set(name, value, opts) {
-  if (typeof (name) !== 'string')
-    throw new TypeError('name (string) required');
-  if (typeof (value) !== 'string')
-    throw new TypeError('value (string) required');
   var self = this;
   var lname = name.toLowerCase();
   this.attrs[lname] = {
@@ -52,8 +62,7 @@ RDN.prototype.set = function set(name, value, opts) {
   }
 };
 
-
-RDN.prototype.equals = function equals(rdn) {
+RDN.prototype.equals = function rdnEquals(rdn) {
   if (typeof (rdn) !== 'object')
     return false;
 
@@ -79,13 +88,10 @@ RDN.prototype.equals = function equals(rdn) {
  * Convert RDN to string according to specified formatting options.
  * (see: DN.format for option details)
  */
-RDN.prototype.format = function format(options) {
-  if (options) {
-    if (typeof (options) !== 'object')
-      throw new TypeError('options must be an object');
-  } else {
-    options = {};
-  }
+RDN.prototype.format = function rdnFormat(options) {
+  assert.optionalObject(options, 'options must be an object');
+  options = options || {};
+
   var self = this;
   var str = '';
 
@@ -154,8 +160,7 @@ RDN.prototype.format = function format(options) {
   return str;
 };
 
-
-RDN.prototype.toString = function toString() {
+RDN.prototype.toString = function rdnToString() {
   return this.format();
 };
 
@@ -314,26 +319,18 @@ function parse(name) {
 }
 
 
-
-///--- API
-
-
 function DN(rdns) {
-  if (!Array.isArray(rdns))
-    throw new TypeError('rdns ([object]) required');
-  rdns.forEach(function (rdn) {
-    if (typeof (rdn) !== 'object')
-      throw new TypeError('rdns ([object]) required');
-  });
+  assert.optionalArrayOfObject(rdns, '[object] required');
 
-  this.rdns = rdns.slice();
+  this.rdns = rdns ? rdns.slice() : [];
   this._format = {};
-
-  this.__defineGetter__('length', function () {
-    return this.rdns.length;
-  });
 }
-
+Object.defineProperties(DN.prototype, {
+  length: {
+    get: function getLength() { return this.rdns.length; },
+    configurable: false
+  }
+});
 
 /**
  * Convert DN to string according to specified formatting options.
@@ -358,21 +355,11 @@ function DN(rdns) {
  * - upperName: RDN names will be uppercased instead of lowercased.
  * - skipSpace: Disable trailing space after RDN separators
  */
-DN.prototype.format = function (options) {
-  if (options) {
-    if (typeof (options) !== 'object')
-      throw new TypeError('options must be an object');
-  } else {
-    options = this._format;
-  }
+DN.prototype.format = function dnFormat(options) {
+  assert.optionalObject(options, 'options must be an object');
+  options = options || this._format;
+
   var str = '';
-  function repeatChar(c, n) {
-    var out = '';
-    var max = n ? n : 0;
-    for (var i = 0; i < max; i++)
-      out += c;
-    return out;
-  }
   this.rdns.forEach(function (rdn) {
     var rdnString = rdn.format(options);
     if (str.length !== 0) {
@@ -390,22 +377,19 @@ DN.prototype.format = function (options) {
   return str;
 };
 
-
 /**
  * Set default string formatting options.
  */
 DN.prototype.setFormat = function setFormat(options) {
-  if (typeof (options) !== 'object')
-    throw new TypeError('options must be an object');
+  assert.object(options, 'options must be an object');
+
   this._format = options;
 };
 
-
-DN.prototype.toString = function () {
+DN.prototype.toString = function dnToString() {
   return this.format();
 };
 
-
 DN.prototype.parentOf = function parentOf(dn) {
   if (typeof (dn) !== 'object')
     dn = parse(dn);
@@ -425,20 +409,17 @@ DN.prototype.parentOf = function parentOf(dn) {
   return true;
 };
 
-
 DN.prototype.childOf = function childOf(dn) {
   if (typeof (dn) !== 'object')
     dn = parse(dn);
   return dn.parentOf(this);
 };
 
-
 DN.prototype.isEmpty = function isEmpty() {
   return (this.rdns.length === 0);
 };
 
-
-DN.prototype.equals = function (dn) {
+DN.prototype.equals = function dnEquals(dn) {
   if (typeof (dn) !== 'object')
     dn = parse(dn);
 
@@ -453,8 +434,7 @@ DN.prototype.equals = function (dn) {
   return true;
 };
 
-
-DN.prototype.parent = function () {
+DN.prototype.parent = function dnParent() {
   if (this.rdns.length !== 0) {
     var save = this.rdns.shift();
     var dn = new DN(this.rdns);
@@ -465,47 +445,38 @@ DN.prototype.parent = function () {
   return null;
 };
 
-
-DN.prototype.clone = function () {
+DN.prototype.clone = function dnClone() {
   var dn = new DN(this.rdns);
   dn._format = this._format;
   return dn;
 };
 
-
-DN.prototype.reverse = function () {
+DN.prototype.reverse = function dnReverse() {
   this.rdns.reverse();
   return this;
 };
 
-
-DN.prototype.pop = function () {
+DN.prototype.pop = function dnPop() {
   return this.rdns.pop();
 };
 
-
-DN.prototype.push = function (rdn) {
-  if (typeof (rdn) !== 'object')
-    throw new TypeError('rdn (RDN) required');
+DN.prototype.push = function dnPush(rdn) {
+  assert.object(rdn, 'rdn (RDN) required');
 
   return this.rdns.push(rdn);
 };
 
-
-DN.prototype.shift = function () {
+DN.prototype.shift = function dnShift() {
   return this.rdns.shift();
 };
 
-
-DN.prototype.unshift = function (rdn) {
-  if (typeof (rdn) !== 'object')
-    throw new TypeError('rdn (RDN) required');
+DN.prototype.unshift = function dnUnshift(rdn) {
+  assert.object(rdn, 'rdn (RDN) required');
 
   return this.rdns.unshift(rdn);
 };
 
-
-DN.isDN = function (dn) {
+DN.isDN = function isDN(dn) {
   if (!dn || typeof (dn) !== 'object') {
     return false;
   }
@@ -523,11 +494,7 @@ DN.isDN = function (dn) {
 ///--- Exports
 
 module.exports = {
-
   parse: parse,
-
   DN: DN,
-
   RDN: RDN
-
 };
diff --git a/test/dn.test.js b/test/dn.test.js
index 796d212..d86ddcf 100644
--- a/test/dn.test.js
+++ b/test/dn.test.js
@@ -3,13 +3,11 @@
 var test = require('tape').test;
 
 
-
 ///--- Globals
 
 var dn;
 
 
-
 ///--- Tests
 
 test('load library', function (t) {
@@ -205,6 +203,51 @@ test('format persists across clone', function (t) {
 });
 
 
+test('initialization', function (t) {
+  var dn1 = new dn.DN();
+  t.ok(dn1);
+  t.equals(dn1.toString(), '');
+  t.ok(dn1.isEmpty(), 'DN with no initializer defaults to null DN');
+
+  var data = [
+    new dn.RDN({ foo: 'bar' }),
+    new dn.RDN({ o: 'base' })
+  ];
+  var dn2 = new dn.DN(data);
+  t.ok(dn2);
+  t.equals(dn2.toString(), 'foo=bar, o=base');
+  t.ok(!dn2.isEmpty());
+
+  t.end();
+});
+
+
+test('array functions', function (t) {
+  var dn1 = dn.parse('a=foo, b=bar, c=baz');
+  t.ok(dn1);
+  t.equal(dn1.toString(), 'a=foo, b=bar, c=baz');
+
+  t.ok(dn1.reverse());
+  t.equal(dn1.toString(), 'c=baz, b=bar, a=foo');
+
+  var rdn = dn1.pop();
+  t.ok(rdn);
+  t.equal(dn1.toString(), 'c=baz, b=bar');
+
+  t.ok(dn1.push(rdn));
+  t.equal(dn1.toString(), 'c=baz, b=bar, a=foo');
+
+  rdn = dn1.shift();
+  t.ok(rdn);
+  t.equal(dn1.toString(), 'b=bar, a=foo');
+
+  t.ok(dn1.unshift(rdn));
+  t.equal(dn1.toString(), 'c=baz, b=bar, a=foo');
+
+  t.end();
+});
+
+
 test('isDN duck-testing', function (t) {
   var valid = dn.parse('cn=foo');
   var isDN = dn.DN.isDN;