The San Diego Chargers have been discussing a long-term contract extension with Keenan Allen, according to multiple sources.

A four- or five-year deal has been discussed for the 2013 third-round pick.

Allen, 24, totaled 215 receptions, 2,554 yards and 16 touchdowns over his first three NFL seasons. He injured his collarbone late in the 2014 season causing him to miss a pair of games, while a kidney issues cost him eight games in 2015.

San Diego has roughly $12 million in salary-cap space. Allen is set to become a free agent after the 2016 season.