Summary: In [Comput. Electr. Eng. 36, No.~1, 155‒159 (2010; Zbl 1195.68041)], {\it D.-L. Vo} et al. proposed an enhancement of an authenticated multiple-key exchange protocol based on {\it N.-Y. Lee} et al.’s protocol [ibid. 34, No.~1, 12‒20 (2008; Zbl 1130.68050)]. In this paper, we show that Vo et al.’s multiple-key exchange protocol cannot resist reflection attack. This means that their protocol fails to provide mutual authentication. Furthermore, we propose an improvement of Vo et al.’s protocol. Our proposed protocol with reflection attack resilience can really provide mutual authentication.