A waste heat recovery apparatus, for use with an internal combustion engine, includes a working fluid circuit to circulate working fluid, a boiler connected on the working fluid circuit and adapted to recover waste heat from a source to heat working fluid, an expander connected on the working fluid circuit to receive working fluid from the boiler, and, a heating jacket associated with the expander. The working fluid circuit downstream of the boiler includes a first branch connecting to an inlet of the expander and a second branch connecting to the heating jacket. A valve is connected on the working fluid circuit to selectively control working fluid flow to one of the first branch for expansion and recovering work or to the second branch to heat the expander responsive to a temperature of the working fluid.