Also the latest version of engine could be build with: --8<---------------cut here---------------start------------->8--- (define-public urho3d-checkout (let ((commit "4af4148048a6443154c6f0498d32626d10f1e86b") (revision "1")) (package (inherit urho3d) (name "urho3d-checkout") (version (string-append (package-version urho3d) "-" revision "." (string-take commit 7))) (source (origin (method git-fetch) (uri (git-reference (url "https://github.com/urho3d/Urho3D") (commit commit))) (file-name (string-append name "-" version "-checkout")) (sha256 (base32 "1nchxswrkfgzsxghi6c55b27zy9127ni7yvnb4xw2xdddyfm1wl0")))))))--8<---------------cut here---------------end--------------->8--- Thanks, Oleg.