Petition signatures export won't filter by petition

When listing petition signatures, as in:

civicrm/activity/search?survey=5&force=1

Results are shown for the petition I selected. However, if I click on the "All nnn records" radio button, and then try to export or print the signatures, signatures for ALL the petitions will be exported. I'm guessing the 'survey=5' parameter doesn't get included in the activity search at that point.