Minnesota Vikings running back Aaron Jones was hit with a $23,186 fine from the NFL for unnecessary roughness stemming from the team’s Week 9 win (27–24) over the Detroit Lions, according to a report from NFL Network’s Tom Pelissero.

The penalty was issued because Jones lowered his helmet during a first-quarter play, which violates the league’s rule on the impermissible use of the helmet. The infraction took place on a third-and-10 when Minnesota trailed 7–0. After catching a short pass from rookie quarterback J.J. McCarthy, Jones picked up a first down but dipped his head just before being tackled by Detroit safety Thomas Harper.

Although no flag was thrown during the game, the league reviewed the play afterward and determined that Jones breached Article 10 of the NFL rulebook. That rule bans players from initiating contact with an opponent by lowering the head or facemask, an effort meant to reduce the risk of head and neck injuries.

Even though Jones seemed to be bracing for contact rather than initiating it, the NFL has been cracking down on such maneuvers—often through postgame fines instead of live penalties—as part of its ongoing push to curb concussions and remove dangerous tackling habits from the game.