LC_COLLATE and pg_upgrade

Hi all,

I just tried to pg_upgrade a PostgreSQL-8.4 to 9.0.

pg_upgrade stopped with this message:

"old and new cluster lc_collate values do not match"

So i checked the LC_COLLATE on 8.4 and 9.0:

8.4:
postgres=# show lc_collate;
lc_collate 
------------
en_US.utf8
(1 row)

9.0:
postgres=# show lc_collate;
lc_collate 
------------
en_US.UTF-8
(1 row)


Well... I think you see my problem, i don't even know if it is really a
problem... 

Is it possible just to change the lc_collate on the 8.4 machine?
Obviously its the same encoding, or am i wrong?

My second Question, but not that urgent is about two databases which
have LC_COLLATE=C, is there a safe way to get it to UTF-8? 

regards
Bernhard