DHCP Radius Mac format

I am trying to get DHCP to work with my radius server. The issue I’m having is that the Mikrotik passes the MAC along to the radius in the format XX:XX:XX as the username and password. I need to set this in the format XXXXXXX. My radius server will not accept a username with “:” only letters and numbers. This is not the same setting and scenario as in the wireless profiles, as I can set the format of the mac address there, just making sure no one post that info on here.