diff --git a/dist/index.js b/dist/index.js
index 3690d71..6ab1ed6 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -64895,18 +64895,16 @@ let BASE_SHA;
         encoding: 'utf-8',
     });
     const HEAD_SHA = headResult.stdout;
-    if ((['pull_request', 'pull_request_target'].includes(eventName) &&
-        !github.context.payload.pull_request.merged) ||
-        eventName == 'merge_group') {
-        try {
-            const mergeBaseRef = yield findMergeBaseRef();
-            const baseResult = (0, child_process_1.spawnSync)('git', ['merge-base', `origin/${mainBranchName}`, mergeBaseRef], { encoding: 'utf-8' });
-            BASE_SHA = baseResult.stdout;
-        }
-        catch (e) {
-            core.setFailed(e.message);
-            return;
-        }
+    if (['pull_request', 'pull_request_target'].includes(eventName) &&
+        !github.context.payload.pull_request.merged) {
+        const baseResult = (0, child_process_1.spawnSync)('git', ['merge-base', `origin/${mainBranchName}`, 'HEAD'], { encoding: 'utf-8' });
+        BASE_SHA = baseResult.stdout;
+    }
+    else if (eventName == 'merge_group') {
+        const baseResult = (0, child_process_1.spawnSync)('git', ['rev-parse', 'HEAD^1'], {
+            encoding: 'utf-8',
+        });
+        BASE_SHA = baseResult.stdout;
     }
     else {
         try {
@@ -65016,35 +65014,6 @@ function findSuccessfulCommit(workflow_id, run_id, owner, repo, branch, lastSucc
         return yield findExistingCommit(octokit, branch, shas);
     });
 }
-function findMergeBaseRef() {
-    return __awaiter(this, void 0, void 0, function* () {
-        if (eventName == 'merge_group') {
-            const mergeQueueBranch = yield findMergeQueueBranch();
-            return `origin/${mergeQueueBranch}`;
-        }
-        else {
-            return 'HEAD';
-        }
-    });
-}
-function findMergeQueuePr() {
-    const { head_ref, base_sha } = github.context.payload.merge_group;
-    const result = new RegExp(`^refs/heads/gh-readonly-queue/${mainBranchName}/pr-(\\d+)-${base_sha}$`).exec(head_ref);
-    return result ? result.at(1) : undefined;
-}
-function findMergeQueueBranch() {
-    return __awaiter(this, void 0, void 0, function* () {
-        const pull_number = findMergeQueuePr();
-        if (!pull_number) {
-            throw new Error('Failed to determine PR number');
-        }
-        process.stdout.write('\n');
-        process.stdout.write(`Found PR #${pull_number} from merge queue branch\n`);
-        const octokit = new ProxifiedClient();
-        const result = yield octokit.request(`GET /repos/${owner}/${repo}/pulls/${pull_number}`, { owner, repo, pull_number: +pull_number });
-        return result.data.head.ref;
-    });
-}
 /**
  * Get first existing commit
  */
diff --git a/find-successful-workflow.ts b/find-successful-workflow.ts
index 1aff4d4..fdfde6e 100644
--- a/find-successful-workflow.ts
+++ b/find-successful-workflow.ts
@@ -41,22 +41,20 @@ let BASE_SHA: string;
   const HEAD_SHA = headResult.stdout;
 
   if (
-    (['pull_request', 'pull_request_target'].includes(eventName) &&
-      !github.context.payload.pull_request.merged) ||
-    eventName == 'merge_group'
+    ['pull_request', 'pull_request_target'].includes(eventName) &&
+    !github.context.payload.pull_request.merged
   ) {
-    try {
-      const mergeBaseRef = await findMergeBaseRef();
-      const baseResult = spawnSync(
-        'git',
-        ['merge-base', `origin/${mainBranchName}`, mergeBaseRef],
-        { encoding: 'utf-8' },
-      );
-      BASE_SHA = baseResult.stdout;
-    } catch (e) {
-      core.setFailed(e.message);
-      return;
-    }
+    const baseResult = spawnSync(
+      'git',
+      ['merge-base', `origin/${mainBranchName}`, 'HEAD'],
+      { encoding: 'utf-8' },
+    );
+    BASE_SHA = baseResult.stdout;
+  } else if (eventName == 'merge_group') {
+    const baseResult = spawnSync('git', ['rev-parse', 'HEAD^1'], {
+      encoding: 'utf-8',
+    });
+    BASE_SHA = baseResult.stdout;
   } else {
     try {
       BASE_SHA = await findSuccessfulCommit(
@@ -204,38 +202,6 @@ async function findSuccessfulCommit(
   return await findExistingCommit(octokit, branch, shas);
 }
 
-async function findMergeBaseRef(): Promise<string> {
-  if (eventName == 'merge_group') {
-    const mergeQueueBranch = await findMergeQueueBranch();
-    return `origin/${mergeQueueBranch}`;
-  } else {
-    return 'HEAD';
-  }
-}
-
-function findMergeQueuePr(): string {
-  const { head_ref, base_sha } = github.context.payload.merge_group;
-  const result = new RegExp(
-    `^refs/heads/gh-readonly-queue/${mainBranchName}/pr-(\\d+)-${base_sha}$`,
-  ).exec(head_ref);
-  return result ? result.at(1) : undefined;
-}
-
-async function findMergeQueueBranch(): Promise<string> {
-  const pull_number = findMergeQueuePr();
-  if (!pull_number) {
-    throw new Error('Failed to determine PR number');
-  }
-  process.stdout.write('\n');
-  process.stdout.write(`Found PR #${pull_number} from merge queue branch\n`);
-  const octokit = new ProxifiedClient();
-  const result = await octokit.request(
-    `GET /repos/${owner}/${repo}/pulls/${pull_number}`,
-    { owner, repo, pull_number: +pull_number },
-  );
-  return result.data.head.ref;
-}
-
 /**
  * Get first existing commit
  */