$OpenBSD: patch-zmdm_c,v 1.1 2017/04/24 10:14:05 sthen Exp $
--- zmdm.c.orig	Mon Apr 24 11:00:55 2017
+++ zmdm.c	Mon Apr 24 11:02:28 2017
@@ -17,8 +17,10 @@
  * zmodem primitives and other code common to zmtx and zmrx
  */
 
+#include <stdlib.h>
 #include <stdio.h>
 #include <termios.h>
+#include <unistd.h>
 #include <signal.h>
 #ifdef UNITE
 #include <sys/select.h>
