turning off ipv6 on lo0

Can't seem to figure out how to completely disable ipv6 in 12.4-RELEASE.
Tried everything I've found in searches, I think.

rc.conf:

ip6addrctl_enable="NO"
ip6addrctl_prefer_ipv4="YES"
ip6addrctl_prefer_ipv6="NO"
ipv6_activate_all_interfaces="NO"
# neither of the 2 lines below have any effect;
# nor does the absence of them
# lo0 always has ipv6 configured
#ipv6_network_interfaces="none"
#ipv6_network_interfaces=""

An ifconfig shows no ipv6 on any interfaces except lo0:

lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
         options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
         inet6 ::1 prefixlen 128
         inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3
         inet 127.0.0.1 netmask 0xff000000
         groups: lo
         nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>

So how do I get rid of it on lo0?
Should I care?

Gary