syntax error on WHERE clause...

I'm getting syntax errors in what (I thought) is a simple query. This
query works in SQLite, but in psql 8.3.14 gets:

ERROR: syntax error at or near "WHERE"

Here's the query:

SELECT (d4.digit * 10000 + d3.digit * 1000 + d2.digit * 100 + d1.digit
* 10 + d0.digit) AS date
FROM digits AS d0
INNER JOIN digits AS d1
INNER JOIN digits AS d2
INNER JOIN digits AS d3
INNER JOIN digits AS d4
WHERE (d4.digit * 10000 + d3.digit * 1000 + d2.digit * 100
+ d1.digit * 10 + d0.digit) < 33
ORDER BY date;

Any idea what's wrong?

FWIW, Digits is a table populated with 10 digits:

=> select * from digits;
id | digit
----+-------
1 | 0
2 | 1
3 | 2
4 | 3
5 | 4
6 | 5
7 | 6
8 | 7
9 | 8
10 | 9
(10 rows)

I'm sure it's something obvious, but reading

http://www.postgresql.org/docs/8.3/interactive/queries-table-expressions.html

has yet to lead me to enlightenment.