$OpenBSD: patch-src_ptlib_unix_serchan_cxx,v 1.1 2017/05/07 20:48:29 espie Exp $
--- src/ptlib/unix/serchan.cxx.orig	Fri Apr 28 01:30:46 2017
+++ src/ptlib/unix/serchan.cxx	Fri Apr 28 01:31:07 2017
@@ -37,6 +37,7 @@
 #include <ptlib.h>
 #include <fcntl.h>
 #include <signal.h>
+#include <unistd.h>
 #include <sys/ioctl.h>
 
 #if defined(P_LINUX) || defined(P_GNU_HURD)
