Hello Julien, thank you for your check! Julien Lepiller writes: [...] > The result of modify-services is a list, but reading your file, it > seems you add it to the end of the (list ...) thing, Ouch... now **I see**! ...and begin to understand the error message > which is not going > to work: you're ending up with a list of lists. You can either put the > modify-services form outside of that list: [...] > or replace the (append (list ...)) with a (cons* ...): I adopted the latter, it makes (services...) more readeable to me [...] Kudos. Gio' aka `Guix-Fu Panda` -- Giovanni Biscuolo Xelera IT Infrastructures