diff --git a/lib/csharp/src/Server/TServer.cs b/lib/csharp/src/Server/TServer.cs
index afb2b9f..f5f617a 100644
--- a/lib/csharp/src/Server/TServer.cs
+++ b/lib/csharp/src/Server/TServer.cs
@@ -11,7 +11,6 @@
 //  http://developers.facebook.com/thrift/using
 
 using System;
-using System.Collections.Generic;
 using Thrift.Protocol;
 using Thrift.Transport;
 using System.IO;
diff --git a/lib/csharp/src/Server/TSimpleServer.cs b/lib/csharp/src/Server/TSimpleServer.cs
index 95f3962..912b4a3 100644
--- a/lib/csharp/src/Server/TSimpleServer.cs
+++ b/lib/csharp/src/Server/TSimpleServer.cs
@@ -10,8 +10,6 @@
 //  See accompanying file LICENSE or visit the Thrift site at:
 //  http://developers.facebook.com/thrift/using
 using System;
-using System.Collections.Generic;
-using System.Text;
 using Thrift.Transport;
 using Thrift.Protocol;
 
diff --git a/lib/csharp/src/Server/TThreadPoolServer.cs b/lib/csharp/src/Server/TThreadPoolServer.cs
index b44487f..e3c5cde 100644
--- a/lib/csharp/src/Server/TThreadPoolServer.cs
+++ b/lib/csharp/src/Server/TThreadPoolServer.cs
@@ -10,8 +10,6 @@
 //  See accompanying file LICENSE or visit the Thrift site at:
 //  http://developers.facebook.com/thrift/using
 using System;
-using System.Collections.Generic;
-using System.Text;
 using System.Threading;
 using Thrift.Protocol;
 using Thrift.Transport;
diff --git a/lib/csharp/src/Server/TThreadedServer.cs b/lib/csharp/src/Server/TThreadedServer.cs
index a4d33a5..2928f31 100644
--- a/lib/csharp/src/Server/TThreadedServer.cs
+++ b/lib/csharp/src/Server/TThreadedServer.cs
@@ -11,8 +11,8 @@
 //  http://developers.facebook.com/thrift/using
 using System;
 using System.Collections.Generic;
-using System.Text;
 using System.Threading;
+using Thrift.Collections;
 using Thrift.Protocol;
 using Thrift.Transport;
 
@@ -28,7 +28,7 @@
 		private readonly int maxThreads;
 
 		private Queue<TTransport> clientQueue;
-		private HashSet<Thread> clientThreads;
+		private THashSet<Thread> clientThreads;
 		private object clientLock;
 		private Thread workerThread;
 
@@ -73,7 +73,7 @@
 			this.maxThreads = maxThreads;
 			clientQueue = new Queue<TTransport>();
 			clientLock = new object();
-			clientThreads = new HashSet<Thread>();
+			clientThreads = new THashSet<Thread>();
 		}
 
 		/// <summary>