--- configure.orig	2013-04-28 20:20:53.000000000 +0200
+++ configure	2013-05-23 00:23:30.000000000 +0200
@@ -8167,6 +8167,7 @@
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <stdlib.h>
+#include <unistd.h>
 #include <stdarg.h>
 #include <string.h>
 #include <float.h>