diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 4e439a2..8d621e9 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -11,7 +11,7 @@ We follow conventional commit [specification](https://www.conventionalcommits.or
 - pin CTL and peer deps on `flake.nix`
 - `nix flake lock`
 - pin `package-set-repo` flake input to corresponding CTL `packages.dhall` upstream rev
-- `nix build .#package-set --impure`
+- `nix build .#package-set --impure -L --show-trace --verbose --debug`
 - `cp result nix/package-set/default.nix`
 - update `nix/purs-nix/custom-deps.nix` according CTL `{spago/packages}.dhall`
 - `./.github/workflows/test.sh` (you'll need to upgrade `LovelaceAcademy/nix-templates` ctl-full in case of template breaking changes)