ipv6 firewall filter rule

Hello,

I have firewall filter rule for all of my ports inside my ex4200 for prevent ip spoofing and this is my access list :

filter port1 {
term layer2 {
from {
ether-type arp;
}
then accept;
}
term port1 {
from {
source-address {
185.x.x.x/28;
}
}
then accept;
}
}

when i want to add ipv6 prefix to this rule i see following error

set filter port1 term port1 from source-address 2ayy:xxxx:x::100/120
^
invalid ip address or hostname: 2ayy:xxxx:x::100/120 at '2ayy:xxxx:x::100/120'

any idea how can i add ipv6 prefix to my firewall filter rule to prevent ipv6 spoofing?

Thank you.