Just read this: https://gitlab.freedesktop.org/fontconfig/fontconfig/issues/126 Could we do the following: use a profile hook to generate a config file and set the environment variable FONTCONFIG_FILE to this file? (I feel that we can't do that because the path of the hook-generated cannot be known in advance.) I looked at what NixOS does in nixpkgs/pkgs/development/libraries/fontconfig/default.nix: > - NixOS creates /etc/fonts/${configVersion}/fonts.conf link to $out/etc/fonts/fonts.conf, > and other modifications should go to /etc/fonts/${configVersion}/conf.d We don't have a global font folder and we probably don't want to have one, so I guess this is not ideal. The