diff --git a/winpr/include/winpr/tchar.h b/winpr/include/winpr/tchar.h
index 0f0402026..7390ed5f3 100644
--- a/winpr/include/winpr/tchar.h
+++ b/winpr/include/winpr/tchar.h
@@ -37,6 +37,7 @@ typedef CHAR TCHAR;
 
 #ifdef UNICODE
 #define _tprintf	wprintf
+#define _tcslen		_wcslen
 #define _tcsdup		_wcsdup
 #define _tcscmp		wcscmp
 #define _tcscpy		wcscpy
@@ -47,6 +48,7 @@ typedef CHAR TCHAR;
 #define _stprintf_s	swprintf_s
 #else
 #define _tprintf	printf
+#define _tcslen		strlen
 #define _tcsdup		_strdup
 #define _tcscmp		strcmp
 #define _tcscpy		strcpy
diff --git a/winpr/libwinpr/wtsapi/wtsapi.c b/winpr/libwinpr/wtsapi/wtsapi.c
index a76361e3e..03fd6da56 100644
--- a/winpr/libwinpr/wtsapi/wtsapi.c
+++ b/winpr/libwinpr/wtsapi/wtsapi.c
@@ -301,11 +301,11 @@ BOOL VirtualChannelIoctl(HANDLE hChannelHandle, ULONG IoControlCode)
 		return FALSE;
 	}
 
-	ntstatus = NtDeviceIoControlFile(hChannelHandle, 0, 0, 0, &ioStatusBlock, IoControlCode, 0, 0, 0, 0);
+	ntstatus = _NtDeviceIoControlFile(hChannelHandle, 0, 0, 0, &ioStatusBlock, IoControlCode, 0, 0, 0, 0);
 
 	if (ntstatus == STATUS_PENDING)
 	{
-		ntstatus = NtWaitForSingleObject(hChannelHandle, 0, 0);
+		ntstatus = _NtWaitForSingleObject(hChannelHandle, 0, 0);
 
 		if (ntstatus >= 0)
 			ntstatus = ioStatusBlock.status;
@@ -314,14 +314,14 @@ BOOL VirtualChannelIoctl(HANDLE hChannelHandle, ULONG IoControlCode)
 	if (ntstatus == STATUS_BUFFER_OVERFLOW)
 	{
 		ntstatus = STATUS_BUFFER_TOO_SMALL;
-		error = RtlNtStatusToDosError(ntstatus);
+		error = _RtlNtStatusToDosError(ntstatus);
 		SetLastError(error);
 		return FALSE;
 	}
 
 	if (ntstatus < 0)
 	{
-		error = RtlNtStatusToDosError(ntstatus);
+		error = _RtlNtStatusToDosError(ntstatus);
 		SetLastError(error);
 		return FALSE;
 	}