ISC DHCP dhclient: How to supersede DNS name servers with IPv4 and IPv6 addresses?

I want tp supersede the name server information, which I get from the DHCP server with my own configuration. Therefor I'm using the following option in my /etc/dhcp/dhclient.conf: supersede domain-name-servers 1.1.1.1, 2.2.2.2, 3.3.3.3; Everything works well, but I want to add IPv6 addresses as well as this is a dual stack server. The following statement does not work (I get /etc/dhcp/dhclient.conf line 56: semicolon expected. in the syslog): supersede domain-name-servers 1.1.1.1, 2.2.2.2, 3.3.3.3, ::1, 2000::BEEF, FURTHER_IPv6_ADDRESS; So my question is: How to I add IPv6 addresses to the supersede domain-name-servers option in /etc/dhcp/dhclient.conf?