According to ESPN.com's Field Yates, the Browns made Thomas the NFL's highest-paid offensive lineman for the 2018 season by tacking on $3 million—including a $1.5 million roster bonus—to his existing deal.
Thomas, 32, will now earn $13.5 million total next season.
While Yates noted "it's unclear what prompted the raise," it's a logical move for a franchise that wants to see Thomas retire as a member of the team that drafted him third overall in 2007.
"He is a great player, a great leader and still playing at an elite level," Browns vice president Sashi Brown said in September, according to the Plain Dealer's Terry Pluto. "We see Joe retiring as Browns, period."
Thomas is still tentatively scheduled to become an unrestricted free agent in 2019, but the franchise's gesture of goodwill should speak volumes if the six-time first-team All Pro ever does hit the open market.
The Browns announced Oct. 23 that Thomas would miss the remainder of the season because of a torn left triceps.
Prior to hitting the shelf, Thomas played 10,363 consecutive snaps to start his career.
Contract information courtesy of Spotrac.com unless noted otherwise.