division by zero issue

Converting some MySQL code to work with Postgres here.

I have this query:

SELECT
tasks.task_id,
(tasks.task_duration * tasks.task_duration_type /
count(user_tasks.task_id)) as hours_allocated
FROM tasks
LEFT JOIN user_tasks
ON tasks.task_id = user_tasks.task_id
WHERE tasks.task_milestone = '0'
GROUP BY
tasks.task_id,
task_duration,
task_duration_type
;

The problem is that sometimes count(user_tasks.task_id) equals zero,
so I get the division by zero error. Is there a simple way to make
that part of the query fail silently and just equal zero instead of
dividing and producing the error?

TIA..

--
Greg Donald
http://gdconsultants.com/
http://destiney.com/