Management of encryption keys is an essential task for establishing secure communication in a mobile ad hoc network (MANET). Any key management scheme must be equipped with a mechanism to revoke disclosed keys and keys of malicious nodes. In some key revocation schemes, including Liu et al.’s scheme (IEEE Trans Parallel Distrib Syst 24(2):239–249 2013), the key revocation procedure is applied based on the opinions of neighboring nodes. In this paper, we propose a new method to improve the performance of Liu et al.’s scheme in detecting the honesty of accuser nodes. This method considers the occurrence of the attacks based on a nonhomogeneous Poisson process. The accuser node is removed from warning list if the time interval between the reception of two consecutive accusation packets is less than a certain value. We find this threshold value by a mathematical model which is also verified by simulation results.