On 29-06-2022 16:46, peter@polidoro.io wrote: > + `(#:skip-build? #t > + #:cargo-inputs > + (("rust-encoding-rs" ,rust-encoding-rs-0.8) > + ("rust-memchr" ,rust-memchr-2) > + ("rust-serde" ,rust-serde-1)))))) The #:cargo-development-inputs are important for antioxidant (the new build system intended to eventually replace cargo-build-system), to actually run the tests. Try running "guix import crate quick-xml@0.17", IIUC it will add the development-inputs. (I've sent a bug report about "guix import crate ..." removing cargo-development-inputs in the past, but I cannot find it anymore). Also, likely you don't actually need the old version -- going by the code in antioxidant, always using rust-quick-xml@0.22 (instead of older versions) does not cause any problems, but since this is cargo-build-system, you will have to patch the Cargo.toml of the dependent to accept the latest version of rust-quick-xml. Greetings, Maxime.