Hi, On 20 June 2017 at 12:35, Aleksandr Koshkin <tinysnippets at gmail.com> wrote: > I have yet another question on SO, bump it here. > https://stackoverflow.com/questions/44649591/rpython-segfaults-on-os-write The library is supposed to be initialized first. I think you need to call rpython_startup_code() first to do that. A bientôt, Armin.