In a vehicle adapted for a driver or passenger in a wheelchair, an additional support (11) for the back of the wheelchair is fastened to an upper portion of a pillar (12, 13), a lower portion of the pillar being fastened to the floor, and the upper portion of the pillar being turnable relative to the lower portion of the pillar and turnably fastened to a bracket of the B-pillar (10) of the vehicle so that the support (11) can be swung into and out of an operative position by the turning the upper portion relative to the lower portion. The upper and lower portions have interacting inner and outer sleeves (24,19) with grooves (28,21) oriented at an angle to each other. The inner and outer sleeves are interconnected by a through bolt (22) fastened to a device inside the lower portion and arranged to move the bolt along the pillar so that the upper portion (12) of the pillar is turned when the bolt is displaced vertically.