{ description = "Custom locale"; outputs = { self, ... }: { overlays.default = final: prev: { glibcLocales = prev.glibcLocales.overrideAttrs (base: { postPatch = base.postPatch + '' cp ${prev.lib.escapeShellArg ./en_EU} localedata/locales/en_EU echo 'en_EU.UTF-8/UTF-8 \' >>localedata/SUPPORTED ''; }); }; nixosModules.default = { lib, ... }: { nixpkgs.overlays = [ self.overlays.default ]; i18n.defaultLocale = lib.mkDefault "en_EU.UTF-8"; }; }; }