diff --git a/websocket-sharp/Net/NetworkCredential.cs b/websocket-sharp/Net/NetworkCredential.cs
index e66394a9..d2d392ce 100644
--- a/websocket-sharp/Net/NetworkCredential.cs
+++ b/websocket-sharp/Net/NetworkCredential.cs
@@ -4,7 +4,7 @@
  *
  * The MIT License
  *
- * Copyright (c) 2014 sta.blockhead
+ * Copyright (c) 2014-2015 sta.blockhead
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -31,69 +31,76 @@ using System;
 namespace WebSocketSharp.Net
 {
   /// <summary>
-  /// Provides the credentials for HTTP authentication (Basic/Digest).
+  /// Provides the credentials for the HTTP authentication (Basic/Digest).
   /// </summary>
   public class NetworkCredential
   {
     #region Private Fields
 
-    private string    _domain;
-    private string    _password;
-    private string [] _roles;
-    private string    _username;
+    private string   _domain;
+    private string   _password;
+    private string[] _roles;
+    private string   _username;
 
     #endregion
 
     #region Public Constructors
 
     /// <summary>
-    /// Initializes a new instance of the <see cref="NetworkCredential"/> class
-    /// with the specified user name and password.
+    /// Initializes a new instance of the <see cref="NetworkCredential"/> class with
+    /// the specified user name and password.
     /// </summary>
     /// <param name="username">
-    /// A <see cref="string"/> that represents the user name associated with the
-    /// credentials.
+    /// A <see cref="string"/> that represents the user name associated with the credentials.
     /// </param>
     /// <param name="password">
-    /// A <see cref="string"/> that represents the password for the user name
-    /// associated with the credentials.
+    /// A <see cref="string"/> that represents the password for the user name associated with
+    /// the credentials.
     /// </param>
+    /// <exception cref="ArgumentNullException">
+    /// <paramref name="username"/> is <see langword="null"/>.
+    /// </exception>
     /// <exception cref="ArgumentException">
-    /// <paramref name="username"/> is <see langword="null"/> or empty.
+    /// <paramref name="username"/> is empty.
     /// </exception>
     public NetworkCredential (string username, string password)
-      : this (username, password, null, new string [0])
+      : this (username, password, null, new string[0])
     {
     }
 
     /// <summary>
-    /// Initializes a new instance of the <see cref="NetworkCredential"/> class
-    /// with the specified user name, password, domain, and roles.
+    /// Initializes a new instance of the <see cref="NetworkCredential"/> class with
+    /// the specified user name, password, domain, and roles.
     /// </summary>
     /// <param name="username">
-    /// A <see cref="string"/> that represents the user name associated with the
-    /// credentials.
+    /// A <see cref="string"/> that represents the user name associated with the credentials.
     /// </param>
     /// <param name="password">
-    /// A <see cref="string"/> that represents the password for the user name
-    /// associated with the credentials.
+    /// A <see cref="string"/> that represents the password for the user name associated with
+    /// the credentials.
     /// </param>
     /// <param name="domain">
-    /// A <see cref="string"/> that represents the name of the user domain
-    /// associated with the credentials.
+    /// A <see cref="string"/> that represents the name of the user domain associated with
+    /// the credentials.
     /// </param>
     /// <param name="roles">
     /// An array of <see cref="string"/> that contains the role names to which
     /// the user associated with the credentials belongs if any.
     /// </param>
+    /// <exception cref="ArgumentNullException">
+    /// <paramref name="username"/> is <see langword="null"/>.
+    /// </exception>
     /// <exception cref="ArgumentException">
-    /// <paramref name="username"/> is <see langword="null"/> or empty.
+    /// <paramref name="username"/> is empty.
     /// </exception>
     public NetworkCredential (
-      string username, string password, string domain, params string [] roles)
+      string username, string password, string domain, params string[] roles)
     {
-      if (username == null || username.Length == 0)
-        throw new ArgumentException ("Must not be null or empty.", "username");
+      if (username == null)
+        throw new ArgumentNullException ("username");
+
+      if (username.Length == 0)
+        throw new ArgumentException ("An empty string.", "username");
 
       _username = username;
       _password = password;
@@ -109,8 +116,8 @@ namespace WebSocketSharp.Net
     /// Gets the name of the user domain associated with the credentials.
     /// </summary>
     /// <value>
-    /// A <see cref="string"/> that represents the name of the user domain
-    /// associated with the credentials.
+    /// A <see cref="string"/> that represents the name of the user domain associated with
+    /// the credentials.
     /// </value>
     public string Domain {
       get {
@@ -126,8 +133,8 @@ namespace WebSocketSharp.Net
     /// Gets the password for the user name associated with the credentials.
     /// </summary>
     /// <value>
-    /// A <see cref="string"/> that represents the password for the user name
-    /// associated with the credentials.
+    /// A <see cref="string"/> that represents the password for the user name associated with
+    /// the credentials.
     /// </value>
     public string Password {
       get {
@@ -140,14 +147,13 @@ namespace WebSocketSharp.Net
     }
 
     /// <summary>
-    /// Gets the role names to which the user associated with the credentials
-    /// belongs.
+    /// Gets the role names to which the user associated with the credentials belongs.
     /// </summary>
     /// <value>
     /// An array of <see cref="string"/> that contains the role names to which
     /// the user associated with the credentials belongs.
     /// </value>
-    public string [] Roles {
+    public string[] Roles {
       get {
         return _roles;
       }
@@ -161,8 +167,7 @@ namespace WebSocketSharp.Net
     /// Gets the user name associated with the credentials.
     /// </summary>
     /// <value>
-    /// A <see cref="string"/> that represents the user name associated with the
-    /// credentials.
+    /// A <see cref="string"/> that represents the user name associated with the credentials.
     /// </value>
     public string UserName {
       get {