diff --git a/.github/workflows/storybook.yml b/.github/workflows/storybook.yml
index 87481b12c..ca82f4bcf 100644
--- a/.github/workflows/storybook.yml
+++ b/.github/workflows/storybook.yml
@@ -87,12 +87,13 @@ jobs:
         if [ "$CHROMATIC_PARAMETER" = " --skip" ]; then
           echo "skip=true" >> $GITHUB_OUTPUT
         fi
-        BRANCH="${{ github.event.pull_request.head.user.login }}:${{ github.event.pull_request.head.ref }}"
-        if [ "$BRANCH" = "misskey-dev:${{ github.event.pull_request.head.ref }}" ]; then
-          BRANCH="${{ github.event.pull_request.head.ref }}"
+        BRANCH="${{ github.event.pull_request.head.user.login }}:$HEAD_REF"
+        if [ "$BRANCH" = "misskey-dev:$HEAD_REF" ]; then
+          BRANCH="$HEAD_REF"
         fi
         pnpm --filter frontend chromatic --exit-once-uploaded -d storybook-static --branch-name $BRANCH $(echo "$CHROMATIC_PARAMETER")
       env:
+        HEAD_REF: ${{ github.event.pull_request.head.ref }}
         CHROMATIC_PROJECT_TOKEN: ${{ secrets.CHROMATIC_PROJECT_TOKEN }}
     - name: Notify that Chromatic detects changes
       uses: actions/github-script@v7.0.1