Sertonix focused on reliability and correctness in system-level tooling, addressing complex bugs in open source infrastructure. In mozilla/sccache, Sertonix improved Linux build stability by reworking symlinked compiler invocation, parsing command-line arguments directly in Rust to bypass symlink resolution issues and ensure consistent caching behavior. In aws/s2n-tls, Sertonix fixed a cryptographic bug in the C-based HKDF implementation, correcting endianness handling to ensure secure key derivation on big-endian systems. Drawing on expertise in C, Rust, and security engineering, Sertonix delivered targeted, in-depth solutions that enhanced cross-platform compatibility and robustness in critical build and cryptographic workflows.