During September 2025, Piotr Mateja focused on stabilizing cross-platform builds for the google/perfetto repository by addressing a Windows-specific build issue. He resolved a signature mismatch in the StdinThread function between subprocess.h and subprocess_windows.cc, ensuring ABI consistency and preventing downstream build failures for Windows users and continuous integration systems. Working primarily in C++ and leveraging expertise in build systems and cross-platform development, Piotr’s fix closed a critical gap that could have led to future divergence between Windows and non-Windows code paths. His work demonstrated careful debugging and code review, contributing to the reliability and maintainability of Perfetto’s build process.