--- include/sudo_compat.h.orig	2015-03-17 11:02:15.190461995 +0100
+++ include/sudo_compat.h	2015-03-17 11:02:36.493190547 +0100
@@ -27,6 +27,7 @@
 # include <stddef.h>
 #endif
 #include <stdarg.h>
+#include <unistd.h>
 
 /*
  * Macros and functions that may be missing on some operating systems.
