diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
new file mode 100644
index 0000000..21c1e71
--- /dev/null
+++ b/.github/workflows/check.yml
@@ -0,0 +1,24 @@
+name: Check build on testing branch
+on:
+  push:
+    branches: ["testing"]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+# Allow only one concurrent deployment, skipping runs queued between the run in-progress and latest queued.
+# However, do NOT cancel in-progress runs as we want to allow these production deployments to complete.
+concurrency:
+  group: "testing"
+  cancel-in-progress: true
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - uses: DeterminateSystems/determinate-nix-action@v3
+      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - run: nix develop -c R -e 'bookdown::render_book()'
diff --git a/flake.nix b/flake.nix
index 9dedff7..e7999b8 100644
--- a/flake.nix
+++ b/flake.nix
@@ -14,7 +14,7 @@
   };
 
   inputs = {
-    nixpkgs.url = "github:rstats-on-nix/nixpkgs/2025-09-01";
+    nixpkgs.url = "github:rstats-on-nix/nixpkgs/2025-09-22";
   };
 
   outputs = {