diff --git a/scripts/preview-theme.js b/scripts/preview-theme.js
index 4935b77..81d7225 100644
--- a/scripts/preview-theme.js
+++ b/scripts/preview-theme.js
@@ -3,21 +3,25 @@ const github = require("@actions/github");
 const parse = require("parse-diff");
 require("dotenv").config();
 
-const parsePullRequestId = (githubRef) => {
-  const result = /refs\/pull\/(\d+)\/merge/g.exec(githubRef);
-  if (!result) {
-    console.log("Reference not found.");
-    return 297;
+function getPrNumber() {
+  const pullRequest = github.context.payload.pull_request;
+  if (!pullRequest) {
+    return undefined;
   }
-  const [, pullRequestId] = result;
-  return pullRequestId;
-};
+
+  return pullRequest.number;
+}
 
 async function run() {
   try {
     const token = core.getInput("token");
     const octokit = github.getOctokit(token || process.env.PERSONAL_TOKEN);
-    const pullRequestId = parsePullRequestId(process.env.GITHUB_REF);
+    const pullRequestId = getPrNumber();
+
+    if (!pullRequestId) {
+      console.log("PR not found");
+      return;
+    }
 
     let res = await octokit.pulls.get({
       owner: "anuraghazra",