An improved seatbelt adjuster for holding the lap seatbelt to the shoulder belt of an automobile seatbelt. The seatbelt adjuster prevents the shoulder belt from rubbing against the neck of a wearer. The adjuster is made of a single unitary piece and therefore cannot be separated. A frame member formed of resilient material has a front portion, rear portion, top edge, bottom edge and space between the front and back portions for containing the lap seatbelt. A parallel pair of dual gussets and rails is molded into the back portion to increase the stiffness of the flap member particularly to prevent it spreading open in hot weather. A snap clip has been added to the flap to avoid inadvertent release in hot weather. A horn gate has been added to the slot to prevent snagging on clothing.