There may be a few more places where this sort of thing will be necessary, but the compiler will be better at finding them than I will. APA> ..\src\sysdep.c(215) : warning C4013: 'fcntl' undefined; assuming extern returning int APA> ..\src\sysdep.c(215) : error C2065: 'F_SETFL' : undeclared identifier 1998-12-07 Martin Buchholz <martin(a)xemacs.org&gt; * sysdep.c (set_descriptor_non_blocking): Since O_NONBLOCK is now always #defined, make use of fcntl conditional on F_SETFL being defined. --- src/sysdep.c.old +++ src/sysdep.c ＠＠ -212,7 +212,9 ＠＠ } #endif +#ifdef F_SETFL fcntl (fd, F_SETFL, O_NONBLOCK); +#endif } #if defined (NO_SUBPROCESSES)