A codeable lock, operable by an authorized key, includes a housing defining a longitudinal axis, a lock cylinder positioned within the housing and selectively rotatable relative to the housing about the longitudinal axis, and a sidebar moveable between a locked position, in which at least a portion of the sidebar is engaged with the lock cylinder and the housing to prevent rotation of the lock cylinder relative to the housing, and an unlocked position, in which the sidebar is disengaged from at least one of the housing and the lock cylinder. The codeable lock also includes a codebar positioned within the lock cylinder. The codebar is moveable from an uncoded state to a coded state upon insertion of the authorized key into the lock cylinder and by securing the codebar to the sidebar. The codeable lock further includes a tumbler positioned within the lock cylinder and engaged with the codebar.