Conf question - how to print hardware address

[Staffan.Ungsgard at teliasonera.com]

In a log message statement I want to print the MAC address of the client making a dhcp request.
Using "log (info, substring(hardware, 1, 6));" I get the MAC address printed as 0:10:e:12:3:12 instead of 00:10:0e:12:03:12 which is the way it is logged by the dhcp server making it's standard log entries (logging DISCOVERs etc).
Can I change this behaviour ?

Best Regards

-- Staffan