--- a/src/ipv6nd.c	
+++ a/src/ipv6nd.c	
@@ -491,9 +491,12 @@ ipv6nd_advertise(struct ipv6_addr *ia)
 
 	/* Make the packet. */
 	ifp = iaf->iface;
+	loginfox("MAKING NA FOR %s", ifp->name);
 	iaf->na_len = sizeof(*na);
+	loginfox("NA LEN %zu (%zu)", iaf->na_len, ifp->hwlen);
 	if (ifp->hwlen != 0)
 		iaf->na_len += (size_t)ROUNDUP8(ifp->hwlen + 2);
+	loginfox("NA LEN FINAL %zu", iaf->na_len);
 	na = calloc(1, iaf->na_len);
 	if (na == NULL) {
 		logerr(__func__);