Worked on the systemd/systemd repository to address build compatibility issues related to legacy environments. Focused on system programming and kernel development using C, the developer implemented a targeted fix for CLONE_PIDFD by defining it in missing_sched.h. This approach resolved build errors encountered when compiling against older versions of glibc and the Linux kernel, specifically pre-2.31 and pre-5.2, respectively. The solution improved build system reliability and ensured successful compilation across a wider range of configurations. By enhancing portability and reducing maintenance overhead, the work contributed to more robust continuous integration and streamlined downstream support for systemd deployments.