diff --git a/.github/workflows/e2e-label-help.yml b/.github/workflows/e2e-label-help.yml
index 1190bcd3d3..4c3a1dfe6f 100644
--- a/.github/workflows/e2e-label-help.yml
+++ b/.github/workflows/e2e-label-help.yml
@@ -59,7 +59,8 @@ jobs:
           esac
 
           mirror_ref="pull-request/$PR_NUMBER"
-          mirror_sha=$(gh api "repos/$GH_REPO/branches/$mirror_ref" --jq '.commit.sha' 2>/dev/null || echo "")
+          mirror_sha=$(gh api "repos/$GH_REPO/git/ref/heads/$mirror_ref" --jq '.object.sha' 2>/dev/null || true)
+          if [[ ! "$mirror_sha" =~ ^[0-9a-f]{40}$ ]]; then mirror_sha=""; fi
           short_pr=${PR_HEAD_SHA:0:7}
 
           if [ -z "$mirror_sha" ]; then