diff --git a/flake.nix b/flake.nix
index 077b90537..c85e5e588 100644
--- a/flake.nix
+++ b/flake.nix
@@ -210,7 +210,7 @@
             src = pkgs.lib.sources.sourceFilesBySuffices ./. [ ".nix" ];
             nativeBuildInputs = [ pkgs.nixfmt-tree ];
             checkPhase = ''
-              treefmt --ci
+              treefmt --ci --tree-root .
             '';
           };