Window Functions final ordering of result set

When running the following query:

select pk, a, d, sum(d) over (partition by a order by pk desc ROWS between 1 preceding and current row) as sum_d from t1;

We get results ordered by (a, pk), not ordered by (a, pk desc). The window function values are computed according to the descending ordering, but the results end up printed as (a, pk). This can be confusing to the end user. How do we deal with this use case and others like it?