diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9d2c42f..2313321 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,11 +9,30 @@ permissions:
   contents: read
 
 jobs:
+  actionlint:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v6
+      - name: Actionlint
+        uses: docker://rhysd/actionlint:1.7.12
+
   test:
     runs-on: ubuntu-latest
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+      - name: Check whitespace
+        run: |
+          set -euo pipefail
+          if [ "${{ github.event_name }}" = "pull_request" ]; then
+            git fetch --no-tags --depth=1 origin "${{ github.base_ref }}"
+            git diff --check "origin/${{ github.base_ref }}...HEAD"
+          else
+            git diff-tree --check --no-commit-id --root -r HEAD
+          fi
       - uses: actions/setup-python@v6
         with:
           python-version: "3.12"