diff --git a/.github/workflows/pr-benchmark-upload-from-main.yml b/.github/workflows/pr-benchmark-upload-from-main.yml
index 231a1b7..570cbe7 100644
--- a/.github/workflows/pr-benchmark-upload-from-main.yml
+++ b/.github/workflows/pr-benchmark-upload-from-main.yml
@@ -34,6 +34,7 @@ jobs:
             let prEvent = JSON.parse(fs.readFileSync(process.env.PR_EVENT, {encoding: 'utf8'}));
             core.exportVariable("PR_HEAD", prEvent.pull_request.head.ref);
             core.exportVariable("PR_BASE", prEvent.pull_request.base.ref);
+            core.exportVariable("PR_BASE_SHA", prEvent.pull_request.base.sha);
             core.exportVariable("PR_DEFAULT", prEvent.pull_request.base.repo.default_branch);
             core.exportVariable("PR_NUMBER", prEvent.number);
       - uses: bencherdev/bencher@main