diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..be52ff1
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,24 @@
+name: CI
+
+# Builds the site on every pull request, so a broken build shows up before the merge.
+on:
+  pull_request:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 24
+          cache: yarn
+      - run: yarn install --frozen-lockfile
+      - run: yarn build