Jitter is a critical problem for the design of both distributed embedded systems and real-time control systems. This work considers meeting the completion jitter constraints of a set of independent, periodic, hard real-time tasks scheduled according to a preemptive fixed-priority scheme. Control over completion jitter is achieved by judiciously applying dynamic voltage scaling (DVS). Through simulation, the proposed method is shown to be an effective tool to meet jitter constraints on a variety of systems.