Context-dependent phonological rules are used to model the mapping from phonemes to their varied phonetic surface realizations. Others, most notably Kaplan and Kay, have described how to compile general context-dependent phonological rewrite rules into finite-state transducers. Such rules are very powerful, but their compilation is complex and can result in very large nondeterministic automata. In this paper we present a simplified rewrite rule system and a technique to efficiently compile such a system into finite-state transducers.