$OpenBSD: patch-extern_h,v 1.1 2016/09/10 13:03:41 ajacoutot Exp $
--- extern.h.orig	Sat Sep 10 11:13:39 2016
+++ extern.h	Sat Sep 10 11:13:49 2016
@@ -1,4 +1,6 @@
 
+#include <sys/select.h> /* fd_set */
+
 #include "macro.h"
 
 typedef unsigned char	n_char;
