diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 32eaf1c..7465335 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -16,7 +16,8 @@ jobs:
           sudo docker run --privileged --name qr -e CI=true -t quine-relay
       - name: push spoiler
         run: |
-          mkdir spoiler
+          git clone https://${GITHUB_ACTOR}:${GITHUB_TOKEN}@github.com/mame/quine-relay.git spoiler --branch spoiler
+          git -C spoiler rm --quiet -r '*'
           sudo docker cp qr:/usr/local/share/quine-relay/QR.rb spoiler/
           sudo docker cp qr:/usr/local/share/quine-relay/QR.rs spoiler/
           sudo docker cp qr:/usr/local/share/quine-relay/QR.scala spoiler/
@@ -146,12 +147,12 @@ jobs:
           sudo docker cp qr:/usr/local/share/quine-relay/QR.rc spoiler/
           sudo docker cp qr:/usr/local/share/quine-relay/QR.rexx spoiler/
           cd spoiler
-          git init --quiet
           git config user.name 'Yusuke Endoh'
           git config user.email 'mame@ruby-lang.org'
           git add .
-          git commit -m spoiler --quiet
-          git push --force --quiet https://${GITHUB_ACTOR}:${GITHUB_TOKEN}@github.com/mame/quine-relay.git master:spoiler
+          TZ=Asia/Tokyo \
+          git commit --allow-empty -m "spoiler: $(git show -s --format=%s "$GITHUB_SHA")"
+          git push --quiet origin spoiler
           echo The intermediate sources are available: https://github.com/mame/quine-relay/tree/spoiler
         if: github.event_name == 'push' && github.ref == 'refs/heads/master'
         env: