diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 9ae7e97..ec4a5ac 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -35,19 +35,30 @@ jobs:
       - name: Check with Clippy
         run: just clippy
 
-  rustfmt:
+  format:
     runs-on: blacksmith-2vcpu-ubuntu-2404
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
+      - name: Install Nix
+        uses: nixbuild/nix-quick-install-action@9f63be77f412a248c9d9a65a4c82cf066cdf8f0c # v35
+
       - name: Install Rust (nightly)
         uses: actions-rust-lang/setup-rust-toolchain@166cdcfd11aee3cb47222f9ddb555ce30ddb9659 # v1.17.0
         with:
           toolchain: nightly
           components: rustfmt
 
-      - name: Check with Rustfmt
-        run: cargo fmt -- --check
+      - name: Enter Nix devshell
+        uses: nicknovitski/nix-develop@9be7cfb4b10451d3390a75dc18ad0465bed4932a # v1.2.1
+        with:
+          arguments: .#ci-format
+
+      - name: Format project
+        run: just fmt
+
+      - name: Check formatting diff
+        run: git diff --exit-code
 
   docs:
     runs-on: blacksmith-2vcpu-ubuntu-2404
diff --git a/flake.nix b/flake.nix
index 60e218b..053b7fc 100644
--- a/flake.nix
+++ b/flake.nix
@@ -34,6 +34,16 @@
             doCheck = true;
           };
 
+          devShells.ci-format = pkgs.mkShell {
+            packages = [
+              config.formatter
+              pkgs.fd
+              pkgs.just
+              pkgs.prettier
+              pkgs.taplo
+            ];
+          };
+
           devShells.default = pkgs.mkShell {
             buildInputs = [ x52just ];