Pastry is an algorithm that provides a scalable distributed hash table over an underlying P2P network. Several implementations of Pastry are available, but to the best of our knowledge the correctness of the algorithm has not been verified formally. Since Pastry combines rather complex data structures, asynchronous communication, concurrency, resilience to churn and fault tolerance, we believe that it makes an interesting target for verification using TLA+. More precisely, our goal is to model the join and lookup protocols of Pastry using the TLA+ language, and to use the associated tools to verify significant correctness properties.