syntax for updating an aliased table

I'm confused about the correct syntax for updating an aliased table. I want
to update triple from triple_updates
where the data is different and tried to use the following....

update triple old
set
old.obln = new.obln, old.ointv = new.ointv,
old.otime = new.otime, old.oflt = new.oflt, old.ostr = new.ostr,
old.oint = new.oint, old.oda = new.oda, old.uasid = new.uasid
from triple_update as new
where (old.s = new.s and
old.g = new.g) and
( old.obln <> new.obln or old.ointv <>
new.ointv or old.otime <> new.otime or old.oflt <> new.oflt or old.ostr
<> new.ostr or old.oint <> new.oint or old.oda <> new.oda or old.uasid <>
new.uasid)

...but postgres complains about not having column "old" in the triple table.
Putting an "as" between triple and old on the first line didn't make any
difference. If
I leave out the old alias, it complains about the columns being ambiguous.
How should the query above be changed to be syntactically correct?

Thanks,
Andy