"sitecustomize.py" is a native input, so look it up in 'native-inputs', not 'inputs'. * gnu/packages/python.scm (customize-site): Look up "sizecustomize.py" in 'native-inputs', not 'inputs'. --- gnu/packages/python.scm | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)