Problems on Mac OS X with SDL_LoadBMP_RW or SDL_RWFromMem

I’m using the following line in a function where I’m passing in a in
memory stream of Bitmap.

return SDL_LoadBMP_RW( SDL_RWFromMem( ms->Memory, ms->Size ), 1 );

This works fine on Win32 on Windows XP Professional ( if that makes any
difference ), but on Mac OS X this same line incorrectly reads the
bitmap information from the stream.

Has anyone come across this issue before when working on Mac OS X?