diff --git a/sys/netinet6/in6.c b/sys/netinet6/in6.c
--- a/sys/netinet6/in6.c
+++ b/sys/netinet6/in6.c
@@ -1603,7 +1603,7 @@
 			else
 				bzero(&ifra.ifra_dstaddr,
 				      sizeof(ifra.ifra_dstaddr));
-			bcopy(&ia->ia_prefixmask, &ifra.ifra_dstaddr,
+			bcopy(&ia->ia_prefixmask, &ifra.ifra_prefixmask,
 			      ia->ia_prefixmask.sin6_len);
 
 			ifra.ifra_flags = ia->ia6_flags;