A patient interface device (25) includes a patient sealing assembly (35) including a cushion (40) and a frame member (45) coupled thereto, and an adjustable forehead support assembly (100). The adjustable forehead support assembly includes an adjustment mechanism (102) coupled to a forehead cushion (104), the adjustment mechanism including a forehead cushion support member (108) having a base portion (114) coupled to the forehead cushion, a projecting member (116) extending from the base portion, a rotatable knob member (110) having a surface (128) having a helical groove (130) provided therein, and a post (134) coupled to one of the frame member and the projecting member. The post is received within the helical groove, and rotation of the knob member causes a position of the post within the helical grove to change thereby causing relative movement between the projecting member and the frame member and movement of the frame member and the cushion relative to the forehead cushion.
