diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8a4f46d..504b03d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,6 +11,11 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v3
+      - name: Check Nixpkgs input
+        uses: DeterminateSystems/flake-checker-action@v4
+        with:
+          fail-mode: true
+          check-outdated: false # PRs shouldn't fail because main's nixpkgs is out of date
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@main
         with: