Hi, Thank you for the patch. I've got some review points. Try to avoid to modify LD_LIBRARY_PATH --8<---------------cut here---------------start------------->8--- + (arguments + (list + #:phases #~(modify-phases %standard-phases + (add-before 'build 'configure-environment + (lambda _ + (setenv "LD_LIBRARY_PATH" + (string-append #$(this-package-input "augeas") + "/lib"))))))) --8<---------------cut here---------------end--------------->8--- As you may check, the project silently uses pkg-config, xml2-config which provide library search: https://github.com/hercules-team/python-augeas/blob/a1e84a7e58e535658f681731b66eca7b71c095a2/augeas/ffi.py#L6C1-L8C60 --8<---------------cut here---------------start------------->8--- def get_include_dirs(): XML2_CONFIG = os.environ.get('XML2_CONFIG', 'xml2-config') PKG_CONFIG = os.environ.get('PKG_CONFIG', 'pkg-config') --8<---------------cut here---------------end--------------->8--- In that light, augeas needs to be placed in inputs and 2 packages need to be added to native-inputs (pkg-config, and maybe libxml2): --8<---------------cut here---------------start------------->8--- + (propagated-inputs (list augeas python-cffi)) --8<---------------cut here---------------end--------------->8--- In general for the python packages, similar like for the golang - propagated-inputs is a place for any modules (they are just sources and) requuring during runtime of the project you may check it like this: --8<---------------cut here---------------start------------->8--- guix shell python- python -- python3 'import ' --8<---------------cut here---------------end--------------->8--- Nix has 100k packages, and may provide some insight on which inputs and where the package expects ;-) https://github.com/NixOS/nixpkgs/blob/nixos-23.11/pkgs/development/python-modules/augeas/default.nix#L34 -- Oleg