diff --git a/.github/workflows/rainix.yaml b/.github/workflows/rainix.yaml
index 58e2dc8f..34a33c5e 100644
--- a/.github/workflows/rainix.yaml
+++ b/.github/workflows/rainix.yaml
@@ -23,3 +23,14 @@ jobs:
       - uses: DeterminateSystems/magic-nix-cache-action@v2
       - name: Run ${{ matrix.task }}
         run: nix develop -c ${{ matrix.task }}
+  format-check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          submodules: recursive
+          fetch-depth: 0
+
+      - uses: DeterminateSystems/nix-installer-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - run: nix develop -c npm run format-check