carp0: incorrect hash for IPv6

[vivek]

Carp does work nicely with IPv4, but when I add IPv6 address it starts to log

Dec 20 12:37:43 server1 kernel: carp0: incorrect hash

IPv4Command:

ifconfig carp0 create
ifconfig carp0 vhid 1 carpdev em1 pass PASSWD 192.168.2.5/24

IPv6 command:

ifconfig carp0 inet6 $IPv6Address prefixlen 64

However, failover does work for both ipv4 and ipv6. Any suggestions?