Democratic presidential candidate Pete Buttigieg said that the signature policy of his tenure as mayor of South Bend, Indiana, didn’t go as smoothly as he’d hoped.

“No policy is perfect, and we learned some things the hard way,” Buttigieg said Monday night at a CNN town hall event.

As documented on HuffPost and elsewhere, Buttigieg spent much of his first term as mayor addressing the roughly 14% of homes in South Bend that were sitting vacant. Though most South Bend residents agreed that the homes were attracting crime and vandalism and were lowering property values, Buttigieg’s administration relied heavily on fines from code enforcement inspectors. In the years that he implemented the policy, known as 1,000 Houses in 1,000 Days, the majority of fines and demolitions were carried out in minority neighborhoods.

The town hall is the first time the presidential candidate has responded in detail to questions about the initiative. Buttigieg said that when he went door-knocking as part of his first campaign for mayor, low-income and minority residents identified the vacant homes as one of their primary concerns. When he responded to those concerns as mayor, Buttigieg said, he attempted to distinguish between vacant homes that belonged to local residents and those that belonged to out-of-town landlords.

Buttigieg acknowledged that he had made mistakes in implementing the policy and that his administration now talks more with residents when determining whether to levy fines or tear down a home.