diff --git a/Lidgren.Network/NetPeer.Fragmentation.cs b/Lidgren.Network/NetPeer.Fragmentation.cs
index 5b8cd01..8c1ea93 100644
--- a/Lidgren.Network/NetPeer.Fragmentation.cs
+++ b/Lidgren.Network/NetPeer.Fragmentation.cs
@@ -73,6 +73,8 @@ namespace Lidgren.Network
 
 		private void HandleReleasedFragment(NetIncomingMessage im)
 		{
+			VerifyNetworkThread();
+
 			//
 			// read fragmentation header and combine fragments
 			//
diff --git a/Lidgren.Network/NetQueue.cs b/Lidgren.Network/NetQueue.cs
index 524a35c..9f19e45 100644
--- a/Lidgren.Network/NetQueue.cs
+++ b/Lidgren.Network/NetQueue.cs
@@ -20,8 +20,7 @@ USE OR OTHER DEALINGS IN THE SOFTWARE.
 using System;
 using System.Diagnostics;
 using System.Collections.Generic;
-
-// @TODO: examine performance characteristics of using SpinLock when using .Net 4.0
+using System.Threading;
 
 namespace Lidgren.Network
 {
@@ -46,7 +45,7 @@ namespace Lidgren.Network
 		// [7] item
 		//
 		private T[] m_items;
-		private readonly object m_lock;
+		private readonly ReaderWriterLockSlim m_lock = new ReaderWriterLockSlim();
 		private int m_size;
 		private int m_head;
 
@@ -65,7 +64,6 @@ namespace Lidgren.Network
 		/// </summary>
 		public NetQueue(int initialCapacity)
 		{
-			m_lock = new object();
 			m_items = new T[initialCapacity];
 		}
 
@@ -74,7 +72,8 @@ namespace Lidgren.Network
 		/// </summary>
 		public void Enqueue(T item)
 		{
-			lock (m_lock)
+			m_lock.EnterWriteLock();
+			try
 			{
 				if (m_size == m_items.Length)
 					SetCapacity(m_items.Length + 8);
@@ -83,6 +82,10 @@ namespace Lidgren.Network
 				m_items[slot] = item;
 				m_size++;
 			}
+			finally
+			{
+				m_lock.ExitWriteLock();
+			}
 		}
 
 		/// <summary>
@@ -90,7 +93,8 @@ namespace Lidgren.Network
 		/// </summary>
 		public void Enqueue(IEnumerable<T> items)
 		{
-			lock (m_lock)
+			m_lock.EnterWriteLock();
+			try
 			{
 				foreach (var item in items)
 				{
@@ -102,6 +106,10 @@ namespace Lidgren.Network
 					m_size++;
 				}
 			}
+			finally
+			{
+				m_lock.ExitWriteLock();
+			}
 		}
 
 		/// <summary>
@@ -109,7 +117,8 @@ namespace Lidgren.Network
 		/// </summary>
 		public void EnqueueFirst(T item)
 		{
-			lock (m_lock)
+			m_lock.EnterWriteLock();
+			try
 			{
 				if (m_size >= m_items.Length)
 					SetCapacity(m_items.Length + 8);
@@ -120,9 +129,13 @@ namespace Lidgren.Network
 				m_items[m_head] = item;
 				m_size++;
 			}
+			finally
+			{
+				m_lock.ExitWriteLock();
+			}
 		}
 
-		// must be called from within a lock(m_lock) !
+		// must be called from within a write locked m_lock!
 		private void SetCapacity(int newCapacity)
 		{
 			if (m_size == 0)
@@ -163,7 +176,8 @@ namespace Lidgren.Network
 				return false;
 			}
 
-			lock (m_lock)
+			m_lock.EnterWriteLock();
+			try
 			{
 				if (m_size == 0)
 				{
@@ -179,6 +193,10 @@ namespace Lidgren.Network
 
 				return true;
 			}
+			finally
+			{
+				m_lock.ExitWriteLock();
+			}
 		}
 
 		/// <summary>
@@ -189,7 +207,8 @@ namespace Lidgren.Network
 			if (m_size == 0)
 				return 0;
 
-			lock (m_lock)
+			m_lock.EnterWriteLock();
+			try
 			{
 				int added = m_size;
 				while (m_size > 0)
@@ -203,6 +222,10 @@ namespace Lidgren.Network
 				}
 				return added;
 			}
+			finally
+			{
+				m_lock.ExitWriteLock();
+			}
 		}
 
 		/// <summary>
@@ -213,12 +236,17 @@ namespace Lidgren.Network
 			if (m_size == 0)
 				return default(T);
 
-			lock (m_lock)
+			m_lock.EnterReadLock();
+			try
 			{
 				if (m_size == 0)
 					return default(T);
 				return m_items[(m_head + offset) % m_items.Length];
 			}
+			finally
+			{
+				m_lock.ExitReadLock();
+			}
 		}
 
 		/// <summary>
@@ -226,7 +254,8 @@ namespace Lidgren.Network
 		/// </summary>
 		public bool Contains(T item)
 		{
-			lock (m_lock)
+			m_lock.EnterReadLock();
+			try
 			{
 				int ptr = m_head;
 				for (int i = 0; i < m_size; i++)
@@ -243,8 +272,12 @@ namespace Lidgren.Network
 					}
 					ptr = (ptr + 1) % m_items.Length;
 				}
+				return false;
+			}
+			finally
+			{
+				m_lock.ExitReadLock();
 			}
-			return false;
 		}
 
 		/// <summary>
@@ -252,7 +285,8 @@ namespace Lidgren.Network
 		/// </summary>
 		public T[] ToArray()
 		{
-			lock (m_lock)
+			m_lock.EnterReadLock();
+			try
 			{
 				T[] retval = new T[m_size];
 				int ptr = m_head;
@@ -264,6 +298,10 @@ namespace Lidgren.Network
 				}
 				return retval;
 			}
+			finally
+			{
+				m_lock.ExitReadLock();
+			}
 		}
 
 		/// <summary>
@@ -271,13 +309,18 @@ namespace Lidgren.Network
 		/// </summary>
 		public void Clear()
 		{
-			lock (m_lock)
+			m_lock.EnterWriteLock();
+			try
 			{
 				for (int i = 0; i < m_items.Length; i++)
 					m_items[i] = default(T);
 				m_head = 0;
 				m_size = 0;
 			}
+			finally
+			{
+				m_lock.ExitWriteLock();
+			}
 		}
 	}
 }