diff -ur liolib.c.orig liolib.c 
--- liolib.c.orig	2017-10-24 15:16:06.036136550 +0200
+++ liolib.c	2017-10-24 15:16:49.968134748 +0200
@@ -16,6 +16,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
 
 #include "lua.h"
