Hi,
It is not clear which compiler you use and what is the structure of your code.
However, I see no problem if you use it for example:
#ifndef _COMDEF_H
#define _COMDEF_H
#include "derivative.h" /* derivative-specific definitions */
#define UBYTE unsigned char
#define SBYTE char
#define UWORD unsigned int
#define SWORD int
#define ULONG unsigned long
#define SLONG long
#define BOOL UBYTE
#endif
If this does not helps then it is necessary to get more precise info.
Best regards,
Ladislav