A woman who turned 21 on the day of Australia’s federal election in May has been declared the nation’s youngest ever senator. And like many female candidates who run for election in Australia, Charlotte Walker wasn’t expected to win.

The former union official won the governing centre-left Labour Party’s third Senate seat for South Australia state in a complicated rank order voting system. A party’s third choice rarely wins. She had the lowest vote count of the six newly elected senators for the state. The Electoral Commission declared the poll on Tuesday.