Joost worked on stabilizing cross-platform build processes for the aseprite/libpng repository, focusing on resolving issues with Apple platform cross-compilation. He addressed a persistent build failure by importing the APPLE variable into the genout.cmake.in script, ensuring that host and target build logic remained consistent across different environments. Using CMake and leveraging his expertise in build systems and cross-compilation, Joost implemented and validated a targeted fix that improved reliability for developers building on non-Apple hosts targeting Apple platforms. His work, though limited in scope to a single bug fix, demonstrated careful attention to platform-specific build workflows and robust engineering practices.