diff --git a/.envrc b/.envrc
new file mode 100644
index 0000000..1d953f4
--- /dev/null
+++ b/.envrc
@@ -0,0 +1 @@
+use nix
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index f9d125b..51ab2c0 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -8,3 +8,10 @@ jobs:
       - uses: nixbuild/nix-quick-install-action@v28
       - name: Structural Integirty Test
         run: cd test && ./bld.sh
+  format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: nixbuild/nix-quick-install-action@v28
+      - name: Code Format Check
+        run: eval "$(nix print-dev-env -f shell.nix)" && treefmt --fail-on-change
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..92b2793
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.direnv
diff --git a/dev/mod.nix b/dev/mod.nix
new file mode 100644
index 0000000..ffcd441
--- /dev/null
+++ b/dev/mod.nix
@@ -0,0 +1 @@
+{ }
diff --git a/dev/shell.nix b/dev/shell.nix
new file mode 100644
index 0000000..48ca0e4
--- /dev/null
+++ b/dev/shell.nix
@@ -0,0 +1,11 @@
+{
+  pkgs ? import <nixpkgs> { },
+}:
+pkgs.mkShell {
+  packages = with pkgs; [
+    treefmt
+    npins
+    nixfmt-rfc-style
+    shfmt
+  ];
+}
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 0000000..2ef387b
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,4 @@
+let
+  dev = import ./. ./dev;
+in
+dev.shell
diff --git a/test/bld.res.nix b/test/bld.res.nix
index e3fd384..00ddbee 100644
--- a/test/bld.res.nix
+++ b/test/bld.res.nix
@@ -42,6 +42,6 @@
     g = 5;
     h = 8;
   };
-  test = scopedImport {std = builtins;} "${../std/set/filterMap.nix}";
+  test = scopedImport { std = builtins; } "${../std/set/filterMap.nix}";
   x = builtins.readFile ./bld/bum;
 }
diff --git a/treefmt.toml b/treefmt.toml
new file mode 100644
index 0000000..6328c02
--- /dev/null
+++ b/treefmt.toml
@@ -0,0 +1,11 @@
+[formatter.nix]
+command = "nixfmt"
+options = []
+includes = [ "*.nix" ]
+excludes = []
+
+[formatter.sh]
+command = "shfmt"
+options = []
+includes = [ "*.sh" ]
+excludes = []