using named windows in with clauses

Is using named windows not allowed in with clauses? create table testa (a integer, b integer); works: with x as ( select sum(b) over (partition by b) from testa ) select * from x; fails with: ERROR: Window "w1" does not exist with x as ( select sum(b) over w1 from testa window w1 as (partition by b) ) select * from x