Worked on the macvim-dev/macvim repository to address compatibility issues with Ruby 4.0, focusing on build system reliability. Implemented a targeted fix in C to ensure the rb_check_typeddata function is always defined, resolving build-time errors encountered with newer Ruby versions. This change improved cross-version compatibility and reduced build failures for users integrating Ruby with MacVim. The solution involved careful management of C-API integration and thorough cross-version testing to maintain stability. By closing two reported issues, the work contributed to long-term maintenance and usability for developers relying on Ruby integration, demonstrating proficiency in C programming and build system management.