Abstract. Information flow exhibited by multithreaded programs is subtle because the attacker may exploit scheduler properties when deducing secret information from publicly observable outputs. Volpano and Smith have introduced a protect command that prevents the scheduler from observing sensitive timing behavior of protected commands and therefore prevents undesired information flows. While a useful construct, protect is nonstandard and difficult to implement. This paper presents a transformation that eliminates the need for protect under cooperative scheduling. We show that both termination-insensitive and termination-sensitive security can be enforced by variants of the transformation in a language with dynamic thread creation.