The Buffalo Bills have signed starting safety Aaron Williams to a four-year contract extension.

The move was announced Wednesday, and provides the Bills at least some long-term stability in their defensive backfield. Williams' signing came at a time when Buffalo stands to lose starting safety Jairus Byrd, who is preparing to test free agency next week.

Williams was Buffalo's second-round pick in the 2011 draft, and is entering the final year of his contract. He was rewarded with the extension after success in making the switch from cornerback to safety last season.

In 14 games last season, Williams had a career-best 82 tackles and also tied Byrd for the team lead with four interceptions.

Overall, he has five interceptions and two forced fumbles in 34 career games.