$NetBSD: patch-ai,v 1.3 2006/02/08 18:25:24 drochner Exp $

--- libbalsa/mailbox_mh.c.orig	2005-05-22 23:11:29.000000000 +0200
+++ libbalsa/mailbox_mh.c
@@ -26,6 +26,7 @@
 #define _XOPEN_SOURCE_EXTENDED 1
 /* to compile this on BSD/Darwin */
 #undef _POSIX_SOURCE
+#define _NETBSD_SOURCE 1
 
 #include <unistd.h>
 #include <fcntl.h>