https://bugs.gentoo.org/874972
--- a/cddb_lookup.c
+++ b/cddb_lookup.c
@@ -25,6 +25,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 #include <string.h>
 #include <sys/socket.h>
 #include <signal.h>
+#include <unistd.h>
 
 #define PACKAGE "Audio::CD"