UPDATE w/ subselect doing locking

Would someone mind setting my head on straight with a proper query
please.  Here is my table and the query I have thusfar.  I need it to
match and update specifically only the string I specify for the regex.

bluelist=> select * from spamcontrol;
  id | logical group | count |           add time            |    added
by    |                     regex                     | comment

----+---------------+-------+-------------------------------+----------------+-----------------------------------------------+---------
     |               |     5 | 2001-11-12 00:09:41.326116-05 |
208.179.59.203 | MERCATI FINANZIARI                            |
     |               |     5 | 2001-11-12 00:10:24.292267-05 |
208.179.59.203 | setup fees                                    |


bluelist=> UPDATE spamcontrol SET count=foo.count+1 FROM (SELECT count
FROM spamcontrol WHERE regex='setup fees' FOR UPDATE) as foo;

How do I get it to only update that one row?

Thank you,
David