Functional BIST is a promising solution for self-testing complex digital systems at reduced costs in terms of area and performance degradation. The present paper addresses the computation of optimal seeds for an arbitrary sequential module to be used as hardware test pattern generator. Up to now, only linear feedback shift registers and accumulator-based structures have been used for deterministic test pattern generation by reseeding. In this paper, a method is proposed which can be applied to general finite state machines. Nevertheless the method is absolutely general, for sake of comparison with previous approaches, in this paper an accumulator-based unit is assumed as pattern generator module. Experiments prove the effectiveness of the approach, which outperforms previous results for accumulators, in terms of test size and test time, without sacrificing the fault detection capability.