buildworld with 6.0

[eoghan]

Hi
Ive cvsup my src to 6.0 and ran:
/usr/src make buildword
however im getting the following error:
===> sbin/ipf/ipf (obj)
mkdir: /usr/obj/usr/src/sbin/ipf/ipf: File exists
*** Error code 1

Stop in /usr/src/sbin/ipf/ipf.
*** Error code 1

Stop in /usr/src/sbin/ipf.
*** Error code 1

Stop in /usr/src/sbin.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.

Can someone help me with this? Im currently running 5.4-RELEASE.
Thanks
Eoghan