An adjuster adjusts a length of at least one strap of a safety harness. The at least one strap is selected from the group consisting of at least one shoulder strap, at least one chest strap, at least one waist strap, at least one seat strap, and at least one leg strap. The adjuster comprises a base, a shaft rotatably operatively connected to the shaft and defining a slot configured and arranged to receive the at least one strap, and a locking mechanism interconnecting the base and the shaft. The locking mechanism allows rotation of the shaft in a first direction and prevents rotation of the shaft in a second opposite direction.