diff --git a/.github/workflows/mypy_primer.yml b/.github/workflows/mypy_primer.yml
index c13d59f947ae..d172cab3870f 100644
--- a/.github/workflows/mypy_primer.yml
+++ b/.github/workflows/mypy_primer.yml
@@ -1,7 +1,7 @@
 name: Run mypy_primer
 
 on:
-  # Only run on PR, since we diff against master
+  # Only run on PR, since we diff against main
   pull_request:
     paths:
     - 'stdlib/**'
@@ -41,9 +41,9 @@ jobs:
           MYPY_VERSION=$(grep mypy== requirements-tests.txt | cut -d = -f 3)
           echo "new commit"
           git rev-list --format=%s --max-count=1 $GITHUB_SHA
-          git checkout -b upstream_master origin/master
+          git checkout -b upstream_main origin/main
           echo "base commit"
-          git rev-list --format=%s --max-count=1 upstream_master
+          git rev-list --format=%s --max-count=1 upstream_main
           echo ''
           cd ..
           # fail action if exit code isn't zero or one
@@ -51,7 +51,7 @@ jobs:
             mypy_primer \
             --new v${MYPY_VERSION} --old v${MYPY_VERSION} \
             --custom-typeshed-repo typeshed_to_test \
-            --new-typeshed $GITHUB_SHA --old-typeshed upstream_master \
+            --new-typeshed $GITHUB_SHA --old-typeshed upstream_main \
             --num-shards 4 --shard-index ${{ matrix.shard-index }} \
             --debug \
             --output concise \
diff --git a/README.md b/README.md
index 10de2c399ddb..7c97f2afe1a9 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 [![Tests](https://github.com/python/typeshed/actions/workflows/tests.yml/badge.svg)](https://github.com/python/typeshed/actions/workflows/tests.yml)
 [![Chat at https://gitter.im/python/typing](https://badges.gitter.im/python/typing.svg)](https://gitter.im/python/typing?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-[![Pull Requests Welcome](https://img.shields.io/badge/pull%20requests-welcome-brightgreen.svg)](https://github.com/python/typeshed/blob/master/CONTRIBUTING.md)
+[![Pull Requests Welcome](https://img.shields.io/badge/pull%20requests-welcome-brightgreen.svg)](https://github.com/python/typeshed/blob/main/CONTRIBUTING.md)
 
 ## About
 
@@ -45,7 +45,7 @@ details, see the documentation for your type checker.
 typeshed includes a package `_typeshed` as part of the standard library.
 This package and its submodules contains utility types, but is not
 available at runtime. For more information about how to use this package,
-[see the `stdlib/_typeshed` directory](https://github.com/python/typeshed/tree/master/stdlib/_typeshed).
+[see the `stdlib/_typeshed` directory](https://github.com/python/typeshed/tree/main/stdlib/_typeshed).
 
 ## Discussion
 
diff --git a/scripts/stubsabot.py b/scripts/stubsabot.py
index 1f0b20151369..bb2b7bc4ade4 100644
--- a/scripts/stubsabot.py
+++ b/scripts/stubsabot.py
@@ -480,7 +480,7 @@ async def create_or_update_pull_request(*, title: str, body: str, branch_name: s
 
     async with session.post(
         f"https://api.github.com/repos/{TYPESHED_OWNER}/typeshed/pulls",
-        json={"title": title, "body": body, "head": f"{fork_owner}:{branch_name}", "base": "master"},
+        json={"title": title, "body": body, "head": f"{fork_owner}:{branch_name}", "base": "main"},
         headers=get_github_api_headers(),
     ) as response:
         resp_json = await response.json()
@@ -490,7 +490,7 @@ async def create_or_update_pull_request(*, title: str, body: str, branch_name: s
             # Find the existing PR
             async with session.get(
                 f"https://api.github.com/repos/{TYPESHED_OWNER}/typeshed/pulls",
-                params={"state": "open", "head": f"{fork_owner}:{branch_name}", "base": "master"},
+                params={"state": "open", "head": f"{fork_owner}:{branch_name}", "base": "main"},
                 headers=get_github_api_headers(),
             ) as response:
                 response.raise_for_status()
@@ -606,7 +606,7 @@ async def suggest_typeshed_update(update: Update, session: aiohttp.ClientSession
     title = f"[stubsabot] Bump {update.distribution} to {update.new_version_spec}"
     async with _repo_lock:
         branch_name = f"{BRANCH_PREFIX}/{normalize(update.distribution)}"
-        subprocess.check_call(["git", "checkout", "-B", branch_name, "origin/master"])
+        subprocess.check_call(["git", "checkout", "-B", branch_name, "origin/main"])
         with open(update.stub_path / "METADATA.toml", "rb") as f:
             meta = tomlkit.load(f)
         meta["version"] = update.new_version_spec
@@ -632,7 +632,7 @@ async def suggest_typeshed_obsolete(obsolete: Obsolete, session: aiohttp.ClientS
     title = f"[stubsabot] Mark {obsolete.distribution} as obsolete since {obsolete.obsolete_since_version}"
     async with _repo_lock:
         branch_name = f"{BRANCH_PREFIX}/{normalize(obsolete.distribution)}"
-        subprocess.check_call(["git", "checkout", "-B", branch_name, "origin/master"])
+        subprocess.check_call(["git", "checkout", "-B", branch_name, "origin/main"])
         with open(obsolete.stub_path / "METADATA.toml", "rb") as f:
             meta = tomlkit.load(f)
         obs_string = tomlkit.string(obsolete.obsolete_since_version)