diff --git a/.github/workflows/release-prepare.yml b/.github/workflows/release-prepare.yml
index e1c7b10..0d5ce53 100644
--- a/.github/workflows/release-prepare.yml
+++ b/.github/workflows/release-prepare.yml
@@ -43,6 +43,15 @@ jobs:
           echo "current=${current}" >> "${GITHUB_OUTPUT}"
           echo "new=${new}" >> "${GITHUB_OUTPUT}"
 
+      - name: Check that the release branch is free
+        env:
+          NEW: ${{ steps.version.outputs.new }}
+        run: |
+          if git ls-remote --exit-code --heads origin "release/v${NEW}" >/dev/null 2>&1; then
+            echo "The branch release/v${NEW} already exists. Delete it and run again." >&2
+            exit 1
+          fi
+
       - name: Raise the version
         env:
           NEW: ${{ steps.version.outputs.new }}
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index acc51a1..e73e048 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -50,7 +50,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && 'main' || github.ref }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.merge_commit_sha || github.ref }}
 
       - name: Create the release
         run: |