diff --git a/OpenRA.Game/Game.cs b/OpenRA.Game/Game.cs
index ecbfb8efa8..f8a71a38a2 100644
--- a/OpenRA.Game/Game.cs
+++ b/OpenRA.Game/Game.cs
@@ -68,7 +68,12 @@ namespace OpenRA
 			lastConnectionState = ConnectionState.PreConnecting;
 			ConnectionStateChanged();
 
-			orderManager = new OrderManager(new NetworkConnection(host, port), ChooseReplayFilename());
+			var replayFilename = ChooseReplayFilename();
+			string path = Path.Combine( Game.SupportDir, "Replays" );
+			if( !Directory.Exists( path ) ) Directory.CreateDirectory( path );
+			var replayFile = File.Create( Path.Combine( path, replayFilename ) );
+
+			orderManager = new OrderManager( new ReplayRecorderConnection( new NetworkConnection( host, port ), replayFile ) );
 		}
 
 		static string ChooseReplayFilename()
@@ -117,7 +122,7 @@ namespace OpenRA
 					lastTime += Settings.Game.Timestep;
 					Widget.DoTick(world);
 					Sound.Tick();
-					orderManager.TickImmediate(world);
+					Sync.CheckSyncUnchanged( world, () => { orderManager.TickImmediate( world ); } );
 
 					var isNetTick = LocalTick % NetTickScale == 0;
 
diff --git a/OpenRA.Game/Network/Connection.cs b/OpenRA.Game/Network/Connection.cs
index ea39217c2d..988e4bfc12 100755
--- a/OpenRA.Game/Network/Connection.cs
+++ b/OpenRA.Game/Network/Connection.cs
@@ -26,7 +26,7 @@ namespace OpenRA.Network
 		Connected,
 	}
 
-	interface IConnection
+	interface IConnection : IDisposable
 	{
 		int LocalClientId { get; }
 		ConnectionState ConnectionState { get; }
@@ -73,9 +73,11 @@ namespace OpenRA.Network
 			foreach( var p in packets )
 				packetFn( p.FromClient, p.Data );
 		}
+
+		public virtual void Dispose() { }
 	}
 
-	class NetworkConnection : EchoConnection, IDisposable
+	class NetworkConnection : EchoConnection
 	{
 		TcpClient socket;
 		int clientId;
@@ -145,7 +147,7 @@ namespace OpenRA.Network
 
 		bool disposed = false;
 
-		public void Dispose ()
+		public override void Dispose ()
 		{
 			if (disposed) return;
 			disposed = true;
@@ -160,48 +162,4 @@ namespace OpenRA.Network
 		
 		~NetworkConnection() { Dispose(); }
 	}
-
-	class ReplayConnection : IConnection
-	{
-		//uint nextFrame = 1;
-		FileStream replayStream;
-
-		public ReplayConnection( string replayFilename )
-		{
-			replayStream = File.OpenRead( replayFilename );
-		}
-
-		public int LocalClientId
-		{
-			get { return 0; }
-		}
-
-		public ConnectionState ConnectionState
-		{
-			get { return ConnectionState.Connected; }
-		}
-
-		public void Send( byte[] packet )
-		{
-			// do nothing; ignore locally generated orders
-		}
-
-		public void Receive( Action<int, byte[]> packetFn )
-		{
-			if( replayStream == null ) return;
-
-			var reader = new BinaryReader( replayStream );
-			while( replayStream.Position < replayStream.Length )
-			{
-				var client = reader.ReadInt32();
-				var packetLen = reader.ReadInt32();
-				var packet = reader.ReadBytes( packetLen );
-				packetFn( client, packet );
-
-				if( !Game.orderManager.GameStarted )
-					return;
-			}
-			replayStream = null;
-		}
-	}
 }
diff --git a/OpenRA.Game/Network/OrderManager.cs b/OpenRA.Game/Network/OrderManager.cs
index a0908a5357..1adcb7e467 100755
--- a/OpenRA.Game/Network/OrderManager.cs
+++ b/OpenRA.Game/Network/OrderManager.cs
@@ -35,8 +35,6 @@ namespace OpenRA.Network
 			new Dictionary<int, Dictionary<int, byte[]>>();
 		List<Order> localOrders = new List<Order>();
 
-		FileStream replaySaveFile;
-
 		public void StartGame()
 		{
 			if (GameStarted) return;
@@ -51,14 +49,6 @@ namespace OpenRA.Network
 			Connection = conn;
 		}
 
-		public OrderManager( IConnection conn, string replayFilename )
-			: this( conn )
-		{
-			string path = Game.SupportDir + "Replays" + Path.DirectorySeparatorChar;
-			if (!Directory.Exists(path)) Directory.CreateDirectory(path);
-			replaySaveFile = File.Create( path + replayFilename );
-		}
-
 		public void IssueOrders( Order[] orders )
 		{
 			foreach( var order in orders )
@@ -94,11 +84,8 @@ namespace OpenRA.Network
 				} );
 
 			foreach( var p in immediatePackets )
-			{
 				foreach( var o in p.Second.ToOrderList( world ) )
 					UnitOrders.ProcessOrder( world, p.First, o );
-				WriteImmediateToReplay( immediatePackets );
-			}
 		}
 
 		Dictionary<int, byte[]> syncForFrame = new Dictionary<int, byte[]>();
@@ -189,7 +176,6 @@ namespace OpenRA.Network
 
 			var ss = sync.SerializeSync( FrameNumber );
 			Connection.Send( ss );
-			WriteToReplay( frameData, ss );
 
 			syncReport.UpdateSyncReport();
 
@@ -198,43 +184,12 @@ namespace OpenRA.Network
 			++FrameNumber;
 		}
 
-		void WriteToReplay( Dictionary<int, byte[]> frameData, byte[] syncData )
-		{
-			if( replaySaveFile == null ) return;
-
-			foreach( var f in frameData )
-			{
-				replaySaveFile.Write( BitConverter.GetBytes( f.Key ) );
-				replaySaveFile.Write( BitConverter.GetBytes( f.Value.Length ) );
-				replaySaveFile.Write( f.Value );
-			}
-			replaySaveFile.Write( BitConverter.GetBytes( (int)0 ) );
-			replaySaveFile.Write( BitConverter.GetBytes( (int)syncData.Length ) );
-			replaySaveFile.Write( syncData );
-		}
-
-		void WriteImmediateToReplay( List<Pair<int, byte[]>> immediatePackets )
-		{
-			if( replaySaveFile == null ) return;
-
-			foreach( var i in immediatePackets )
-			{
-				replaySaveFile.Write( BitConverter.GetBytes( i.First ) );
-				replaySaveFile.Write( BitConverter.GetBytes( i.Second.Length ) );
-				replaySaveFile.Write( i.Second );
-			}
-		}
-
 		bool disposed;
 		public void Dispose()
 		{
 			if (disposed) return;
 
-			if (replaySaveFile != null)
-				replaySaveFile.Dispose();
-
-			var disposableConnection = Connection as IDisposable;
-			if (disposableConnection != null) disposableConnection.Dispose();
+			Connection.Dispose();
 
 			disposed = true;
 			GC.SuppressFinalize(this);
diff --git a/OpenRA.Game/Network/ReplayConnection.cs b/OpenRA.Game/Network/ReplayConnection.cs
new file mode 100755
index 0000000000..1e42f528ad
--- /dev/null
+++ b/OpenRA.Game/Network/ReplayConnection.cs
@@ -0,0 +1,103 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.IO;
+
+namespace OpenRA.Network
+{
+	class ReplayConnection : IConnection
+	{
+		//uint nextFrame = 1;
+		FileStream replayStream;
+
+		public ReplayConnection( string replayFilename )
+		{
+			replayStream = File.OpenRead( replayFilename );
+		}
+
+		public int LocalClientId
+		{
+			get { return 0; }
+		}
+
+		public ConnectionState ConnectionState
+		{
+			get { return ConnectionState.Connected; }
+		}
+
+		public void Send( byte[] packet )
+		{
+			// do nothing; ignore locally generated orders
+		}
+
+		public void Receive( Action<int, byte[]> packetFn )
+		{
+			if( replayStream == null ) return;
+
+			var reader = new BinaryReader( replayStream );
+			while( replayStream.Position < replayStream.Length )
+			{
+				var client = reader.ReadInt32();
+				var packetLen = reader.ReadInt32();
+				var packet = reader.ReadBytes( packetLen );
+				packetFn( client, packet );
+
+				if( !Game.orderManager.GameStarted )
+					return;
+			}
+			replayStream = null;
+		}
+
+		public void Dispose() { }
+	}
+
+	class ReplayRecorderConnection : IConnection
+	{
+		IConnection inner;
+		FileStream replayFile;
+		BinaryWriter writer;
+
+		public ReplayRecorderConnection( IConnection inner, FileStream replayFile )
+		{
+			this.inner = inner;
+			this.replayFile = replayFile;
+			this.writer = new BinaryWriter( replayFile );
+		}
+
+		public int LocalClientId { get { return inner.LocalClientId; } }
+		public ConnectionState ConnectionState { get { return inner.ConnectionState; } }
+
+		public void Send( byte[] packet )
+		{
+			inner.Send( packet );
+		}
+
+		public void Receive( Action<int, byte[]> packetFn )
+		{
+			inner.Receive( ( client, data ) =>
+				{
+					writer.Write( client );
+					writer.Write( data.Length );
+					writer.Write( data );
+					packetFn( client, data );
+				} );
+		}
+
+		bool disposed;
+
+		public void Dispose()
+		{
+			if( disposed )
+				return;
+
+			writer.Close();
+			disposed = true;
+		}
+
+		~ReplayRecorderConnection()
+		{
+			Dispose();
+		}
+	}
+}
diff --git a/OpenRA.Game/OpenRA.Game.csproj b/OpenRA.Game/OpenRA.Game.csproj
index 5de01b3dca..60fd31ea8a 100755
--- a/OpenRA.Game/OpenRA.Game.csproj
+++ b/OpenRA.Game/OpenRA.Game.csproj
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
     <Platform Condition=" '$(Platform)' == '' ">x86</Platform>
-    <ProductVersion>9.0.21022</ProductVersion>
+    <ProductVersion>9.0.30729</ProductVersion>
     <SchemaVersion>2.0</SchemaVersion>
     <ProjectGuid>{0DFB103F-2962-400F-8C6D-E2C28CCBA633}</ProjectGuid>
     <OutputType>WinExe</OutputType>
@@ -222,6 +222,7 @@
     <Compile Include="ActorReference.cs" />
     <Compile Include="ModData.cs" />
     <Compile Include="Map.cs" />
+    <Compile Include="Network\ReplayConnection.cs" />
     <Compile Include="Network\Session.cs" />
     <Compile Include="ObjectCreator.cs" />
     <Compile Include="Network\SyncReport.cs" />
diff --git a/OpenRA.Game/Sync.cs b/OpenRA.Game/Sync.cs
index efe072cefd..63dc9f0ac4 100755
--- a/OpenRA.Game/Sync.cs
+++ b/OpenRA.Game/Sync.cs
@@ -140,6 +140,7 @@ namespace OpenRA
 		public static T CheckSyncUnchanged<T>( World world, Func<T> fn )
 		{
 			int sync = world.SyncHash();
+			bool prevInUnsyncedCode = inUnsyncedCode;
 			inUnsyncedCode = true;
 			try
 			{
@@ -147,9 +148,9 @@ namespace OpenRA
 			}
 			finally
 			{
-				inUnsyncedCode = false;
+				inUnsyncedCode = prevInUnsyncedCode;
 				if( sync != world.SyncHash() )
-					throw new InvalidOperationException( "Desync in DispatchMouseInput" );
+					throw new InvalidOperationException( "CheckSyncUnchanged: sync-changing code may not run here" );
 			}
 		}