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.