Hi, > +(define-public tgcli > [...] > + (replace 'check > + (lambda _ > + (invoke "pytest")))))) Something I learned some time ago: if you make this > + (replace 'check > + (lambda* (#:key tests? #:allow-other-keys) > + (when tests? > + (invoke "pytest"))))))) then "guix build tgcli --without-tests" can be used, IIRC. Greetings, Maxime.