diff --git a/channels/audin/server/audin.c b/channels/audin/server/audin.c
index 8bf392972..9f7506abb 100644
--- a/channels/audin/server/audin.c
+++ b/channels/audin/server/audin.c
@@ -77,9 +77,11 @@ static void audin_server_select_format(audin_server_context* context, int client
 
 static void audin_server_send_version(audin_server* audin, wStream* s)
 {
+	ULONG written;
+
 	Stream_Write_UINT8(s, MSG_SNDIN_VERSION);
 	Stream_Write_UINT32(s, 1); /* Version (4 bytes) */
-	WTSVirtualChannelWrite(audin->audin_channel, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), NULL);
+	WTSVirtualChannelWrite(audin->audin_channel, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), &written);
 }
 
 static BOOL audin_server_recv_version(audin_server* audin, wStream* s, UINT32 length)
@@ -101,6 +103,7 @@ static void audin_server_send_formats(audin_server* audin, wStream* s)
 {
 	int i;
 	UINT32 nAvgBytesPerSec;
+	ULONG written;
 
 	Stream_SetPosition(s, 0);
 	Stream_Write_UINT8(s, MSG_SNDIN_FORMATS);
@@ -131,7 +134,7 @@ static void audin_server_send_formats(audin_server* audin, wStream* s)
 		}
 	}
 
-	WTSVirtualChannelWrite(audin->audin_channel, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), NULL);
+	WTSVirtualChannelWrite(audin->audin_channel, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), &written);
 }
 
 static BOOL audin_server_recv_formats(audin_server* audin, wStream* s, UINT32 length)
@@ -181,6 +184,8 @@ static BOOL audin_server_recv_formats(audin_server* audin, wStream* s, UINT32 le
 
 static void audin_server_send_open(audin_server* audin, wStream* s)
 {
+	ULONG written;
+
 	if (audin->context.selected_client_format < 0)
 		return;
 
@@ -203,7 +208,7 @@ static void audin_server_send_open(audin_server* audin, wStream* s)
 	Stream_Write_UINT16(s, 16); /* wBitsPerSample */
 	Stream_Write_UINT16(s, 0); /* cbSize */
 
-	WTSVirtualChannelWrite(audin->audin_channel, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), NULL);
+	WTSVirtualChannelWrite(audin->audin_channel, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), &written);
 }
 
 static BOOL audin_server_recv_open_reply(audin_server* audin, wStream* s, UINT32 length)
diff --git a/channels/cliprdr/server/cliprdr_main.c b/channels/cliprdr/server/cliprdr_main.c
index 5375237d8..0e94fabea 100644
--- a/channels/cliprdr/server/cliprdr_main.c
+++ b/channels/cliprdr/server/cliprdr_main.c
@@ -68,6 +68,7 @@ static int cliprdr_server_send_capabilities(CliprdrServerContext* context)
 	BOOL status;
 	UINT32 generalFlags;
 	CLIPRDR_HEADER header;
+	ULONG written;
 
 	printf("CliprdrServerSendCapabilities\n");
 
@@ -96,7 +97,7 @@ static int cliprdr_server_send_capabilities(CliprdrServerContext* context)
 
 	Stream_SealLength(s);
 
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), &written);
 
 	Stream_Free(s, TRUE);
 
@@ -108,6 +109,7 @@ static int cliprdr_server_send_monitor_ready(CliprdrServerContext* context)
 	wStream* s;
 	BOOL status;
 	CLIPRDR_HEADER header;
+	ULONG written;
 
 	printf("CliprdrServerSendMonitorReady\n");
 
@@ -123,7 +125,7 @@ static int cliprdr_server_send_monitor_ready(CliprdrServerContext* context)
 
 	Stream_SealLength(s);
 
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), &written);
 
 	Stream_Free(s, TRUE);
 
@@ -135,6 +137,7 @@ static int cliprdr_server_send_format_list_response(CliprdrServerContext* contex
 	wStream* s;
 	BOOL status;
 	CLIPRDR_HEADER header;
+	ULONG written;
 
 	printf("CliprdrServerSendFormatListResponse\n");
 
@@ -150,7 +153,7 @@ static int cliprdr_server_send_format_list_response(CliprdrServerContext* contex
 
 	Stream_SealLength(s);
 
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), &written);
 
 	Stream_Free(s, TRUE);
 
diff --git a/channels/rdpdr/server/rdpdr_main.c b/channels/rdpdr/server/rdpdr_main.c
index f7bee4aea..9b67388f0 100644
--- a/channels/rdpdr/server/rdpdr_main.c
+++ b/channels/rdpdr/server/rdpdr_main.c
@@ -34,6 +34,7 @@ static int rdpdr_server_send_announce_request(RdpdrServerContext* context)
 	wStream* s;
 	BOOL status;
 	RDPDR_HEADER header;
+	ULONG written;
 
 	printf("RdpdrServerSendAnnounceRequest\n");
 
@@ -51,7 +52,7 @@ static int rdpdr_server_send_announce_request(RdpdrServerContext* context)
 
 	Stream_SealLength(s);
 
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), &written);
 
 	Stream_Free(s, TRUE);
 
@@ -295,6 +296,7 @@ static int rdpdr_server_send_core_capability_request(RdpdrServerContext* context
 	BOOL status;
 	RDPDR_HEADER header;
 	UINT16 numCapabilities;
+	ULONG written;
 
 	printf("RdpdrServerSendCoreCapabilityRequest\n");
 
@@ -319,7 +321,7 @@ static int rdpdr_server_send_core_capability_request(RdpdrServerContext* context
 
 	Stream_SealLength(s);
 
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), &written);
 
 	Stream_Free(s, TRUE);
 
@@ -376,6 +378,7 @@ static int rdpdr_server_send_client_id_confirm(RdpdrServerContext* context)
 	wStream* s;
 	BOOL status;
 	RDPDR_HEADER header;
+	ULONG written;
 
 	printf("RdpdrServerSendClientIdConfirm\n");
 
@@ -393,7 +396,7 @@ static int rdpdr_server_send_client_id_confirm(RdpdrServerContext* context)
 
 	Stream_SealLength(s);
 
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), &written);
 
 	Stream_Free(s, TRUE);
 
@@ -457,6 +460,7 @@ static int rdpdr_server_send_user_logged_on(RdpdrServerContext* context)
 	wStream* s;
 	BOOL status;
 	RDPDR_HEADER header;
+	ULONG written;
 
 	printf("%s\n", __FUNCTION__);
 
@@ -470,7 +474,7 @@ static int rdpdr_server_send_user_logged_on(RdpdrServerContext* context)
 
 	Stream_SealLength(s);
 
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_Length(s), &written);
 
 	Stream_Free(s, TRUE);
 
diff --git a/channels/rdpsnd/server/rdpsnd_main.c b/channels/rdpsnd/server/rdpsnd_main.c
index ad887ed35..9c09afc89 100644
--- a/channels/rdpsnd/server/rdpsnd_main.c
+++ b/channels/rdpsnd/server/rdpsnd_main.c
@@ -36,6 +36,7 @@ static BOOL rdpsnd_server_send_formats(RdpsndServerContext* context, wStream* s)
 	int pos;
 	UINT16 i;
 	BOOL status;
+	ULONG written;
 
 	Stream_Write_UINT8(s, SNDC_FORMATS);
 	Stream_Write_UINT8(s, 0);
@@ -74,7 +75,7 @@ static BOOL rdpsnd_server_send_formats(RdpsndServerContext* context, wStream* s)
 	Stream_SetPosition(s, 2);
 	Stream_Write_UINT16(s, pos - 4);
 	Stream_SetPosition(s, pos);
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), &written);
 	Stream_SetPosition(s, 0);
 
 	return status;
@@ -361,6 +362,7 @@ static BOOL rdpsnd_server_send_audio_pdu(RdpsndServerContext* context)
 	BOOL status;
 	AUDIO_FORMAT* format;
 	int tbytes_per_frame;
+	ULONG written;
 	wStream* s = context->priv->rdpsnd_pdu;
 
 	format = &context->client_formats[context->selected_client_format];
@@ -422,7 +424,7 @@ static BOOL rdpsnd_server_send_audio_pdu(RdpsndServerContext* context)
 	Stream_Seek(s, 3); /* bPad */
 	Stream_Write(s, src, 4);
 
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), &written);
 	if (!status)
 		goto out;
 	Stream_SetPosition(s, 0);
@@ -435,7 +437,7 @@ static BOOL rdpsnd_server_send_audio_pdu(RdpsndServerContext* context)
 	if (fill_size > 0)
 		Stream_Zero(s, fill_size);
 
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), &written);
 
 out:
 	Stream_SetPosition(s, 0);
@@ -476,6 +478,7 @@ static BOOL rdpsnd_server_set_volume(RdpsndServerContext* context, int left, int
 {
 	int pos;
 	BOOL status;
+	ULONG written;
 	wStream* s = context->priv->rdpsnd_pdu;
 
 	Stream_Write_UINT8(s, SNDC_SETVOLUME);
@@ -489,7 +492,7 @@ static BOOL rdpsnd_server_set_volume(RdpsndServerContext* context, int left, int
 	Stream_SetPosition(s, 2);
 	Stream_Write_UINT16(s, pos - 4);
 	Stream_SetPosition(s, pos);
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), &written);
 	Stream_SetPosition(s, 0);
 
 	return status;
@@ -499,6 +502,7 @@ static BOOL rdpsnd_server_close(RdpsndServerContext* context)
 {
 	int pos;
 	BOOL status;
+	ULONG written;
 	wStream* s = context->priv->rdpsnd_pdu;
 
 	if (context->selected_client_format < 0)
@@ -520,7 +524,7 @@ static BOOL rdpsnd_server_close(RdpsndServerContext* context)
 	Stream_SetPosition(s, 2);
 	Stream_Write_UINT16(s, pos - 4);
 	Stream_SetPosition(s, pos);
-	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), NULL);
+	status = WTSVirtualChannelWrite(context->priv->ChannelHandle, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), &written);
 	Stream_SetPosition(s, 0);
 
 	return status;
diff --git a/libfreerdp/core/server.c b/libfreerdp/core/server.c
index 6242b3c2c..4e4e520e5 100644
--- a/libfreerdp/core/server.c
+++ b/libfreerdp/core/server.c
@@ -427,9 +427,11 @@ BOOL WTSVirtualChannelManagerCheckFileDescriptor(HANDLE hServer)
 
 		if (channel)
 		{
+			ULONG written;
+
 			vcm->drdynvc_channel = channel;
 			dynvc_caps = 0x00010050; /* DYNVC_CAPS_VERSION1 (4 bytes) */
-			WTSVirtualChannelWrite(channel, (PCHAR) &dynvc_caps, sizeof(dynvc_caps), NULL);
+			WTSVirtualChannelWrite(channel, (PCHAR) &dynvc_caps, sizeof(dynvc_caps), &written);
 		}
 	}
 
@@ -916,6 +918,7 @@ HANDLE WINAPI FreeRDP_WTSVirtualChannelOpenEx(DWORD SessionId, LPSTR pVirtualNam
 	BOOL joined = FALSE;
 	freerdp_peer* client;
 	rdpPeerChannel* channel;
+	ULONG written;
 	WTSVirtualChannelManager* vcm;
 
 	if (SessionId == WTS_CURRENT_SESSION)
@@ -968,7 +971,7 @@ HANDLE WINAPI FreeRDP_WTSVirtualChannelOpenEx(DWORD SessionId, LPSTR pVirtualNam
 
 	s = Stream_New(NULL, 64);
 	wts_write_drdynvc_create_request(s, channel->channelId, pVirtualName);
-	WTSVirtualChannelWrite(vcm->drdynvc_channel, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), NULL);
+	WTSVirtualChannelWrite(vcm->drdynvc_channel, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), &written);
 	Stream_Free(s, TRUE);
 
 	return channel;
@@ -997,9 +1000,11 @@ BOOL WINAPI FreeRDP_WTSVirtualChannelClose(HANDLE hChannelHandle)
 
 			if (channel->dvc_open_state == DVC_OPEN_STATE_SUCCEEDED)
 			{
+				ULONG written;
+
 				s = Stream_New(NULL, 8);
 				wts_write_drdynvc_header(s, CLOSE_REQUEST_PDU, channel->channelId);
-				WTSVirtualChannelWrite(vcm->drdynvc_channel, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), NULL);
+				WTSVirtualChannelWrite(vcm->drdynvc_channel, (PCHAR) Stream_Buffer(s), Stream_GetPosition(s), &written);
 				Stream_Free(s, TRUE);
 			}
 		}
diff --git a/server/Sample/sfreerdp.c b/server/Sample/sfreerdp.c
index cd8c81725..3a2d36d06 100644
--- a/server/Sample/sfreerdp.c
+++ b/server/Sample/sfreerdp.c
@@ -405,6 +405,7 @@ static void* tf_debug_channel_thread_func(void* arg)
 	wStream* s;
 	void* buffer;
 	DWORD BytesReturned = 0;
+	ULONG written;
 	testPeerContext* context = (testPeerContext*) arg;
 
 	if (WTSVirtualChannelQuery(context->debug_channel, WTSVirtualFileHandle, &buffer, &BytesReturned) == TRUE)
@@ -417,7 +418,7 @@ static void* tf_debug_channel_thread_func(void* arg)
 
 	s = Stream_New(NULL, 4096);
 
-	WTSVirtualChannelWrite(context->debug_channel, (PCHAR) "test1", 5, NULL);
+	WTSVirtualChannelWrite(context->debug_channel, (PCHAR) "test1", 5, &written);
 
 	while (1)
 	{
@@ -583,7 +584,8 @@ void tf_peer_keyboard_event(rdpInput* input, UINT16 flags, UINT16 code)
 	{
 		if (context->debug_channel)
 		{
-			WTSVirtualChannelWrite(context->debug_channel, (PCHAR) "test2", 5, NULL);
+			ULONG written;
+			WTSVirtualChannelWrite(context->debug_channel, (PCHAR) "test2", 5, &written);
 		}
 	}
 	else if ((flags & 0x4000) && code == 0x2D) /* 'x' key */