IMO, defining your own aliases for stdint.h types is innocent enough, but manually defining prototypes for Win32 calls instead of including standard headers is one step too far. You don’t own the ABI here: things like HANDLE and WPARAM have already changed sizes once, who’s to say ULONG_PTR will stay the same as uintptr_t for all future architectures? There is a good reason why doing the same on Unix is discouraged.