$OpenBSD: patch-boost_asio_detail_pipe_select_interrupter_hpp,v 1.2 2013/03/08 01:21:37 brad Exp $
--- boost/asio/detail/pipe_select_interrupter.hpp.orig	Wed Oct 10 15:22:58 2012
+++ boost/asio/detail/pipe_select_interrupter.hpp	Wed Oct 10 15:23:33 2012
@@ -23,6 +23,7 @@
 #if !defined(BOOST_ASIO_HAS_EVENTFD)
 
 #include <boost/asio/detail/push_options.hpp>
+#include <unistd.h>
 
 namespace boost {
 namespace asio {
