Dunedin's public libraries expect thousands of people to take advantage of a scheme to pay old fines with donations to foodbanks.
Under the month-long amnesty, each donated can of food wipes off $5 of outstanding fines.
The scheme comes ahead of a tougher fine collection system which starts in September.
At least 15,000 people have outstanding fines totalling $385,000, while several thousand have debts large enough to be barred from borrowing.
The libraries' customer services head, Mike Collett, says the system was begun to retrieve lost books and get people borrowing again.
Mr Collett says the scheme has been tried in many American libraries and a university library in the North Island.
He expects several thousand food cans to be collected for local foodbanks.