--- src/argyll/spectro/usbio.c.orig 2009-03-07 21:18:13.000000000 +0300 +++ src/argyll/spectro/usbio.c 2009-03-07 21:18:41.000000000 +0300 @@ -20,6 +20,7 @@ #include <stdio.h> #include <stdlib.h> +#include <unistd.h> #include <time.h> #include <signal.h> #if defined(UNIX)