Control under partial observations is studied within the infinite-string supervisory control framework. It is shown that, provided that there are no pure liveness assumptions embodied in the plant model (technically, the omega-language generated by the plant is the limit of the finite-string language generated), the problem of synthesizing a centralized supervisor reduces to the case of complete observations; the result involves constructions similar to those used to "determinize" nondeterministic automata on infinite strings.