diff --git a/.github/workflows/backport.yml b/.github/workflows/backport.yml
index ad802512..d7fa314a 100644
--- a/.github/workflows/backport.yml
+++ b/.github/workflows/backport.yml
@@ -40,6 +40,6 @@ jobs:
         uses: korthout/backport-action@v3
         with:
           github_token: ${{ steps.app-token.outputs.token }}
-          pull_title: "[${target-branch}] ${pull_title}"
+          pull_title: "[${target_branch}] ${pull_title}"
           pull_description: |-
             This is an automated backport of #${pull_number}.