The proliferation of wireless devices with static spectrum assignment strategy leads to spectrum scarcity. Dynamic spectrum access using cognitive radio algorithms can increase the spectrum utilization. In many applications where a Cognitive Radio Ad Hoc Network (CRAHN) should be deployed, all channels belong to primary users (PU) and secondary users (SU) can use them if they are not used by PUs. All channels are treated the same and there is no predefined control channel to coordinate the rendezvous of SUs before exchanging data. Many distributed rendezvous algorithms have been proposed to address this problem. One of the good proposed algorithms is NGQFH which considers usage statistics of channels for improved rendezvous performance. In this article we evaluate the NGQFH and analyze its performance in the presence of an intelligent jammer who is aware of channel usage statistics. We then propose an enhanced algorithm that has a much better rendezvous performance in the presence of a jammer. We show that the proposed algorithm is simple, effective and has a negligible impact on the rendezvous performance.