diff --git a/zebra/rtadv.c b/zebra/rtadv.c
index 4bab03b..e5a026e 100644
--- a/zebra/rtadv.c
+++ b/zebra/rtadv.c
@@ -1110,7 +1110,7 @@
       rprefix = getdata (node);
       vty_out (vty, " ipv6 nd prefix %s/%d",
 	       inet_ntop (AF_INET6, &rprefix->prefix.u.prefix6, 
-			  buf, INET6_ADDRSTRLEN),
+			  (char *) buf, INET6_ADDRSTRLEN),
 	       rprefix->prefix.prefixlen);
       if ((rprefix->AdvValidLifetime != RTADV_VALID_LIFETIME) || 
 	  (rprefix->AdvPreferredLifetime != RTADV_PREFERRED_LIFETIME))