Index: protocol.c
--- protocol.c.orig	2010-08-08 17:45:33.000000000 +0200
+++ protocol.c	2010-08-10 09:35:54.000000000 +0200
@@ -38,6 +38,9 @@
 #include <missing.h> /* declarations for missing library functions */
 
 #include <sys/socket.h>
+#ifndef PF_UNSPEC
+#define PF_UNSPEC 0
+#endif
 #if HAVE_LWRES_NETDB_H
 # include <lwres/netdb.h>
 #elif !HAVE_GETADDRINFO
