rc.conf inet6 confusion

i386 9-current as of today

/etc/rc.conf

    network_interfaces="bge0 lo0"   # List of network interfaces (lo0 is loopback).
    ifconfig_lo0="inet 127.0.0.1"   # default loopback device configuration.        
    ipv4_addrs_bge0="147.28.0.36/24 147.28.0.40/24"                                 
    ifconfig_bge0_ipv6="2001:418:1::36/64"                                          
    ifconfig_bge0_alias0="inet6 2001:418:1::40/64"                                  

which gets me

    ifconfig: 2001:418:1::36/64: bad value (width too large)

and

    bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
	    options=8009b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,LINKSTATE>
	    ether 00:30:48:86:b7:5a
	    inet6 fe80::230:48ff:fe86:b75a%bge0 prefixlen 64 scopeid 0x1 
	    inet 147.28.0.36 netmask 0xffffff00 broadcast 147.28.0.255
	    inet 147.28.0.40 netmask 0xffffff00 broadcast 147.28.0.255
	    inet6 2001:418:1::40 prefixlen 64 
	    nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
	    media: Ethernet autoselect (1000baseT <full-duplex>)
	    status: active

clue bat, please

randy