diff --git a/ci/default.nix b/ci/default.nix
index ec35121bb24b..cddea6453606 100644
--- a/ci/default.nix
+++ b/ci/default.nix
@@ -76,7 +76,13 @@ in
   inherit pkgs fmt;
   requestReviews = pkgs.callPackage ./request-reviews { };
   codeownersValidator = pkgs.callPackage ./codeowners-validator { };
-  eval = pkgs.callPackage ./eval { };
+
+  # FIXME(lf-): it might be useful to test other Nix implementations
+  # (nixVersions.stable and Lix) here somehow at some point to ensure we don't
+  # have eval divergence.
+  eval = pkgs.callPackage ./eval {
+    nix = pkgs.nixVersions.latest;
+  };
 
   # CI jobs
   lib-tests = import ../lib/tests/release.nix { inherit pkgs; };
diff --git a/ci/eval/default.nix b/ci/eval/default.nix
index cbb77bc89bd3..efe216c98f5c 100644
--- a/ci/eval/default.nix
+++ b/ci/eval/default.nix
@@ -1,15 +1,23 @@
+# Evaluates all the accessible paths in nixpkgs.
+# *This only builds on Linux* since it requires the Linux sandbox isolation to
+# be able to write in various places while evaluating inside the sandbox.
+#
+# This file is used by nixpkgs CI (see .github/workflows/eval.yml) as well as
+# being used directly as an entry point in Lix's CI (in `flake.nix` in the Lix
+# repo).
+#
+# If you know you are doing a breaking API change, please ping the nixpkgs CI
+# maintainers and the Lix maintainers (`nix eval -f . lib.teams.lix`).
 {
   callPackage,
   lib,
   runCommand,
   writeShellScript,
-  writeText,
   symlinkJoin,
   time,
   procps,
-  nixVersions,
+  nix,
   jq,
-  python3,
 }:
 
 let
@@ -31,8 +39,6 @@ let
       );
     };
 
-  nix = nixVersions.latest;
-
   supportedSystems = builtins.fromJSON (builtins.readFile ../supportedSystems.json);
 
   attrpathsSuperset =
diff --git a/lib/tests/test-with-nix.nix b/lib/tests/test-with-nix.nix
index 4f9aa53f83dd..d9089902a0a3 100644
--- a/lib/tests/test-with-nix.nix
+++ b/lib/tests/test-with-nix.nix
@@ -3,9 +3,10 @@
 
   IMPORTANT:
   This is used by the github.com/NixOS/nix CI.
+  This is used by Lix's CI (see flake.nix in the Lix repo).
 
   Try not to change the interface of this file, or if you need to, ping the
-  Nix maintainers for help. Thank you!
+  Nix AND Lix maintainers (`nix eval -f . lib.teams.lix`) for help. Thank you!
 */
 {
   pkgs,