Error al compilar [bcc64 Error] C++ requires a type specifier for all declarations

[cocute]

Hola estoy intentando compilar una aplicación de 32bits a 64bits en XE10 y me da este error:
[bcc64 Error] (44): C++ requires a type specifier for all declarations

La linea 44 que da el error es esta:
WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int)

se os ocurre que puedo cambiar ahí para que no de error?

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop
//---------------------------------------------------------------------------

#include <Vcl.Styles.hpp>
#include <Vcl.Themes.hpp>
USEFORM("..\appcmn\tcpoptdlg.cpp", TcpOptDialog);
USEFORM("..\appcmn\serioptdlg.cpp", SerialOptDialog);
USEFORM("..\appcmn\refdlg.cpp", RefDialog);
USEFORM("..\appcmn\viewer.cpp", TextViewer);
USEFORM("logstrdlg.cpp", LogStrDialog);
USEFORM("instrdlg.cpp", InputStrDialog);
USEFORM("..\appcmn\vieweropt.cpp", ViewerOptDialog);
USEFORM("..\appcmn\cmdoptdlg.cpp", CmdOptDialog);
USEFORM("..\appcmn\aboutdlg.cpp", AboutDialog);
USEFORM("..\appcmn\confdlg.cpp", ConfDialog);
USEFORM("..\appcmn\maskoptdlg.cpp", MaskOptDialog);
USEFORM("..\appcmn\keydlg.cpp", KeyDialog);
USEFORM("..\appcmn\ftpoptdlg.cpp", FtpOptDialog);
USEFORM("naviopt.cpp", OptDialog);
USEFORM("navimain.cpp", MainForm);
USEFORM("mondlg.cpp", MonitorDialog);
USEFORM("outstrdlg.cpp", OutputStrDialog);
USEFORM("rcvoptdlg.cpp", RcvOptDialog);
//---------------------------------------------------------------------------
WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int)

.....
.........
..........

gracias

[[AgustinOrtu]]

No he usado nunca C++, pero revisa la documentacion:

Upgrading Existing C++ Projects to 64-bit Windows

C++Builder 64-bit Windows Differences