—We describe our experience from the implementation of the T-MAC protocol for wireless sensor networks in the open-source Castalia simulator. Notwithstanding the popularity of the protocol in the research literature in recent years, we find several practical issues that are not addressed in the original protocol description, which lead to a degree of freedom in the protocol design and implementation and have an impact on its resulting performance. These issues include the ability of the underlying physical layer and hardware to efficiently detect the activation events in the protocol, and necessary changes to the collision resolution and clock synchronization procedures in the presence of varying sleep patterns. Our results highlight the need for rigorous detail in protocol descriptions in the research literature and provide important insights into some of the common pitfalls.