extern int xt_compat_add_offset(u_int8_t af, unsigned int offset, short delta);
extern void xt_compat_flush_offsets(u_int8_t af);
-extern short xt_compat_calc_jump(u_int8_t af, unsigned int offset);
+extern int xt_compat_calc_jump(u_int8_t af, unsigned int offset);
extern int xt_compat_match_offset(const struct xt_match *match);
extern int xt_compat_match_from_user(struct xt_entry_match *m,