diff --git a/scripts/open-user-pr.ts b/scripts/open-user-pr.ts
index 9ec5b3b49a2..189fc50f1b0 100644
--- a/scripts/open-user-pr.ts
+++ b/scripts/open-user-pr.ts
@@ -12,28 +12,35 @@ function padNum(num: number) {
 const userName = process.env.GH_USERNAME;
 const reviewers = process.env.REQUESTING_USER ? [process.env.REQUESTING_USER] : ["weswigham", "sandersn", "RyanCavanaugh"];
 const now = new Date();
-const branchName = `user-update-${process.env.TARGET_FORK}-${now.getFullYear()}${padNum(now.getMonth() + 1)}${padNum(now.getDate())}${process.env.TARGET_BRANCH ? "-" + process.env.TARGET_BRANCH : ""}`;
+const masterBranchname = `user-baseline-updates`;
+const branchName = process.env.TARGET_FORK.toLowerCase() === "microsoft" && (process.env.TARGET_BRANCH || "master") === "master"
+    ? masterBranchname
+    : `user-update-${process.env.TARGET_FORK}-${now.getFullYear()}${padNum(now.getMonth() + 1)}${padNum(now.getDate())}${process.env.TARGET_BRANCH ? "-" + process.env.TARGET_BRANCH : ""}`;
 const remoteUrl = `https://${process.argv[2]}@github.com/${userName}/TypeScript.git`;
+const baseRef = branchName === masterBranchname ? "master" : masterBranchname;
 runSequence([
+    ["git", ["remote", "add", "fork", remoteUrl]], // Add the remote fork
     ["git", ["checkout", "."]], // reset any changes
+    ["git", ["fetch", baseRef === "master" ? "origin" : "fork", baseRef]], // fetch target ref in case it's not present locally
+    ["git", ["checkout", baseRef]], // move head to target
     ["node", ["./node_modules/gulp/bin/gulp.js", "baseline-accept"]], // accept baselines
     ["git", ["checkout", "-b", branchName]], // create a branch
     ["git", ["add", "."]], // Add all changes
     ["git", ["commit", "-m", `"Update user baselines"`]], // Commit all changes
-    ["git", ["remote", "add", "fork", remoteUrl]], // Add the remote fork
     ["git", ["push", "--set-upstream", "fork", branchName, "-f"]] // push the branch
 ]);
 
 const gh = new Octokit({
     auth: process.argv[2]
 });
+const prOwner = branchName === masterBranchname ? "microsoft" : userName;
 gh.pulls.create({
-    owner: process.env.TARGET_FORK!,
+    owner: prOwner,
     repo: "TypeScript",
     maintainer_can_modify: true,
     title: `🤖 User test baselines have changed` + (process.env.TARGET_BRANCH ? ` for ${process.env.TARGET_BRANCH}` : ""),
     head: `${userName}:${branchName}`,
-    base: process.env.TARGET_BRANCH || "master",
+    base: branchName === masterBranchname ? "master" : masterBranchname,
     body:
 `${process.env.SOURCE_ISSUE ? `This test run was triggerd by a request on https://github.com/Microsoft/TypeScript/pull/${process.env.SOURCE_ISSUE} `+"\n" : ""}Please review the diff and merge if no changes are unexpected.
 You can view the build log [here](https://typescript.visualstudio.com/TypeScript/_build/index?buildId=${process.env.BUILD_BUILDID}&_a=summary).
@@ -44,7 +51,7 @@ cc ${reviewers.map(r => "@" + r).join(" ")}`,
     console.log(`Pull request ${num} created.`);
     if (!process.env.SOURCE_ISSUE) {
         await gh.pulls.createReviewRequest({
-            owner: process.env.TARGET_FORK!,
+            owner: prOwner,
             repo: "TypeScript",
             pull_number: num,
             reviewers,
@@ -53,7 +60,7 @@ cc ${reviewers.map(r => "@" + r).join(" ")}`,
     else {
         await gh.issues.createComment({
             issue_number: +process.env.SOURCE_ISSUE,
-            owner: "Microsoft",
+            owner: "microsoft",
             repo: "TypeScript",
             body: `The user suite test run you requested has finished and _failed_. I've opened a [PR with the baseline diff from master](${r.data.html_url}).`
         });