MSYS2-DevKit (only Ruby >= 2.4) Stating with RubyInstaller-2.4 we're no longer using our own DevKit compilation, but make use of MSYS2 for both building Ruby itself as well as building Ruby gems with C-extensions. It can be installed by using RubyInstaller with Devkit or through the ridk install command, which is part of RubyInstaller-2.4+. Alternatively a manual download and installation from MSY