diff -ruN libmsn-4.2.1.orig//msn/util.cpp libmsn-4.2.1//msn/util.cpp
--- libmsn-4.2.1.orig//msn/util.cpp	2009-07-22 21:57:10.000000000 +0200
+++ libmsn-4.2.1//msn/util.cpp	2012-05-07 12:45:47.581493381 +0200
@@ -30,6 +30,7 @@
 #include <openssl/rand.h>
 #include <cstring>
 #include <sys/timeb.h>
+#include <unistd.h>
 #include "md5.h"
 #include "libsiren/siren7.h"