Currently, Wikis are the most popular form of collaborative editors. Recently, some researches have been done to shift from traditional centralized architecture to fully decentralized wikis relying on peer-to-peer networks. This architecture improves scalability and fault-tolerance, but subtly changes the behavior of wiki in case of concurrent changes. While traditional wikis ensure that all wiki pages have been reviewed by, at least, a human, some pages in P2P wiki systems can be the result of an automatic merge done by the system. This forces P2P wiki systems to integrate a concurrency awareness system to notify users about the status of wiki pages. The particular context of a P2P wiki system makes traditional awareness mechanisms inadequate. In this paper, we present a new concurrency awareness mechanism designed for P2P wiki systems.