diff --git a/treefmt.toml b/treefmt.toml
new file mode 100644
index 0000000..d838b92
--- /dev/null
+++ b/treefmt.toml
@@ -0,0 +1,4 @@
+[formatter.nix]
+command = "nix"
+options = ["fmt"]
+includes = [ "*.nix" ]