SeqScan with full text search

Hello group!

I have query like this:

SELECT
  employments.candidate_id AS candidate_id,
  SUM(TS_RANK(employers.search_vector, TO_TSQUERY('simple', 'One:* |
Two:* | Three:* | Four:*'), 2)) AS ts_rank
FROM
  employments
INNER JOIN
  employers ON employments.employer_id = employers.id
AND
  employers.search_vector @@ TO_TSQUERY('simple', 'One:* | Two:* |
Three:* | Four:*')
GROUP BY
  candidate_id;

And it results with this:

http://explain.depesz.com/s/jLM

The JOIN between employments and employers is the culprit. I'm unable
to get rid of the seq scan, and setting enable_seqscan to off makes
things even worse.

Is there any way to get rid of this JOIN?

What info should I post to debug this easier?

Thanks!