diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c9df574e2..f3c270b6f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,9 +10,9 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
-      - uses: cachix/install-nix-action@v22
+      - uses: cachix/install-nix-action@v23
         with:
           github_access_token: ${{ secrets.GITHUB_TOKEN }}
 
@@ -40,9 +40,9 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
-      - uses: cachix/install-nix-action@v22
+      - uses: cachix/install-nix-action@v23
         with:
           github_access_token: ${{ secrets.GITHUB_TOKEN }}
 
@@ -54,9 +54,9 @@ jobs:
   ensure-generated:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
-      - uses: cachix/install-nix-action@v22
+      - uses: cachix/install-nix-action@v23
         with:
           github_access_token: ${{ secrets.GITHUB_TOKEN }}
 
@@ -67,3 +67,20 @@ jobs:
 
       - name: Ensure clean
         run: git diff --exit-code
+
+  ensure-fmt:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: cachix/install-nix-action@v23
+        with:
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+
+      - uses: DeterminateSystems/magic-nix-cache-action@v2
+
+      - name: Fmt
+        run: nix develop --command xc fmt
+
+      - name: Ensure clean
+        run: git diff --exit-code
diff --git a/README.md b/README.md
index fbc78f637..102fbe792 100644
--- a/README.md
+++ b/README.md
@@ -96,10 +96,11 @@ go run ./cmd/templ generate -include-version=false && go test ./... -bench=. -be
 
 ### fmt
 
-Format all Go code.
+Format all Go and templ code.
 
-```
+```sh
 gofmt -s -w .
+go run ./cmd/templ fmt .
 ```
 
 ### lint
@@ -124,7 +125,7 @@ Run the development server.
 
 Directory: docs
 
-```
+```sh
 npm run start
 ```
 
@@ -134,7 +135,7 @@ Build production docs site.
 
 Directory: docs
 
-```
+```sh
 npm run build
 ```