Hours always displaying in 24-hour format

I have a field whose hours format is set to 12-hour time, but displays only in 24-hour format. The problem appears to be line 258 of office_hours.module:

if ($field['hoursformat']== 1) {

My tests show me that theme_office_hours_formatter_default() doesn't have access to $field, so there's no way for that check to ever pass.

Now to figure out what variable should be tested instead...