diff --git a/.github/workflows/build_appstore.yml b/.github/workflows/build_appstore.yml
index cec0bf604a..eeeb919c16 100644
--- a/.github/workflows/build_appstore.yml
+++ b/.github/workflows/build_appstore.yml
@@ -163,7 +163,7 @@ jobs:
       env:
         WORKFLOW_URL: https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}
         DESTINATION: ${{ env.destination }}
-        PLATFORM: macos
+        PLATFORM: macOS
       run: |
         bundle exec fastlane run mattermost_send_message \
           mattermost_webhook_url:${{ secrets.MM_WEBHOOK_URL }} \