diff --git a/.gitignore b/.gitignore
index da24b60e..376bdfd8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,14 @@
-## Ignore MonoDevelop build results and temporary files.
+## Ignore build results and temporary files.
 
+Backup*
+_UpgradeReport_Files
 bin
+obj
+
 *.mdb
+*.pdb
 *.pidb
+*.suo
+*.user
 *.userprefs
+UpgradeLog*.*
diff --git a/websocket-sharp/Net/HttpListener.cs b/websocket-sharp/Net/HttpListener.cs
index d55a5b07..a886c668 100644
--- a/websocket-sharp/Net/HttpListener.cs
+++ b/websocket-sharp/Net/HttpListener.cs
@@ -85,8 +85,9 @@ namespace WebSocketSharp.Net {
 		/// Gets or sets the scheme used to authenticate the clients.
 		/// </summary>
 		/// <value>
-		/// One of the <see cref="AuthenticationSchemes"/> values that indicates the scheme used to
-		/// authenticate the clients. The default value is <see cref="AuthenticationSchemes.Anonymous"/>.
+		/// One of the <see cref="WebSocketSharp.Net.AuthenticationSchemes"/> values that indicates
+		/// the scheme used to authenticate the clients.
+		/// The default value is <see cref="WebSocketSharp.Net.AuthenticationSchemes.Anonymous"/>.
 		/// </value>
 		/// <exception cref="ObjectDisposedException">
 		/// This object has been closed.
diff --git a/websocket-sharp/Net/WebHeaderCollection.cs b/websocket-sharp/Net/WebHeaderCollection.cs
index 817ac93a..ece5a592 100644
--- a/websocket-sharp/Net/WebHeaderCollection.cs
+++ b/websocket-sharp/Net/WebHeaderCollection.cs
@@ -410,7 +410,8 @@ namespace WebSocketSharp.Net
 		/// Gets a collection of header names in the collection.
 		/// </summary>
 		/// <value>
-		/// A <see cref="KeysCollection"/> that contains a collection of header names in the collection.
+		/// A <see cref="NameObjectCollectionBase.KeysCollection"/> that contains a collection
+		/// of header names in the collection.
 		/// </value>
 		public override KeysCollection Keys
 		{
diff --git a/websocket-sharp/Server/WebSocketServiceHostManager.cs b/websocket-sharp/Server/WebSocketServiceHostManager.cs
index 11c6966d..45e4eb8d 100644
--- a/websocket-sharp/Server/WebSocketServiceHostManager.cs
+++ b/websocket-sharp/Server/WebSocketServiceHostManager.cs
@@ -703,7 +703,7 @@ namespace WebSocketSharp.Server
       if (message == null || message.Length == 0)
         return Broadping ();
 
-      byte [] data;
+      byte [] data = null;
       var msg = _state.CheckIfStarted () ??
                 (data = Encoding.UTF8.GetBytes (message)).CheckIfValidPingData ();
 
diff --git a/websocket-sharp/Server/WebSocketSessionManager.cs b/websocket-sharp/Server/WebSocketSessionManager.cs
index b5da20cb..00ce5f8e 100644
--- a/websocket-sharp/Server/WebSocketSessionManager.cs
+++ b/websocket-sharp/Server/WebSocketSessionManager.cs
@@ -601,7 +601,7 @@ namespace WebSocketSharp.Server
       if (message == null || message.Length == 0)
         return Broadping ();
 
-      byte [] data;
+      byte [] data = null;
       var msg = _state.CheckIfStarted () ??
                 (data = Encoding.UTF8.GetBytes (message)).CheckIfValidPingData ();