Missing table from in INSERT RETURNING

Hello dear list,
I would appreciate some help on a small matter that has been bothering me
for a long time :

CREATE TABLE test_insert_returning(
gid SERIAL
,some_value int
);
WITH serie AS (
select s, s*10 as computing
from generate_series(1,10) as s
)
INSERT INTO test_insert_returning (some_value)
SELECT computing
FROM serie
RETURNING gid, serie.s

doesn't work.

The only workaround I found was to create a plpgsql function that doesan
idnividual insert
so that :
WITH serie AS (
select s, s*10 as computing
from generate_series(1,10) as s
)
SELECT serie.s, my_inserting_function(computing)
FROM serie ;

But it is very annoying and potentially bad for performance because many
insert may be fired.

Any solution?
(postgres 9.3)
Cheers,
Rémi-C