diff --git a/tests/functional/nix_path.sh b/tests/functional/nix_path.sh
index d5ee20b96af..e67ed9be25d 100755
--- a/tests/functional/nix_path.sh
+++ b/tests/functional/nix_path.sh
@@ -46,6 +46,7 @@ done
 # TODO: port to NixOS somehow; ideally we'd run the test suite in a non-NixOS VM
 if [[ isTestOnNixOS ]]; then
     mkdir -p $NIX_STATE_DIR/profiles/per-user/root/channels/nixpkgs
+    # check that the default values are set
     [[ $(nix-instantiate --eval -E 'with builtins; length nixPath') = 2 ]]
     # setting anything overrides the default paths
     # this ensures we can force an empty search path