diff --git a/.github/workflows/python.yml b/.github/workflows/python.yml
index b15cb21..616e417 100644
--- a/.github/workflows/python.yml
+++ b/.github/workflows/python.yml
@@ -18,11 +18,6 @@ jobs:
             python-version: '3.9'
           - os: macos-latest
             python-version: '3.10'
-        include:
-          - os: macos-13
-            python-version: '3.9'
-          - os: macos-13
-            python-version: '3.10'
     steps:
       - uses: actions/checkout@v6
         with:
diff --git a/boilerplates/git_repo_tests.py b/boilerplates/git_repo_tests.py
index 26c0c3b..fc83b31 100644
--- a/boilerplates/git_repo_tests.py
+++ b/boilerplates/git_repo_tests.py
@@ -3,6 +3,7 @@
 import logging
 import pathlib
 import tempfile
+import typing as t
 import unittest
 
 import git
@@ -13,8 +14,8 @@
 class GitRepoTests(unittest.TestCase):
     """Provide several utility properties and methods named repo_* and git_*."""
 
-    repo = None  # type: git.Repo
-    repo_path = None  # type: pathlib.Path
+    repo: t.Optional[git.Repo] = None
+    repo_path: t.Optional[pathlib.Path] = None
 
     def setUp(self):
         self._tmpdir = tempfile.TemporaryDirectory()  # pylint: disable = consider-using-with
@@ -36,12 +37,13 @@ def tearDown(self):
 
     @property
     def repo_head_hexsha(self) -> str:
+        self.assertIsInstance(self.repo, git.Repo)
+        assert isinstance(self.repo, git.Repo), type(self.repo)
         return self.repo.head.commit.hexsha[:8]
 
     def git_init(self) -> git.Repo:
         """Initialize a git repository in the temporary folder."""
         self.repo = git.Repo.init(str(self.repo_path))
-        self.assertIsInstance(self.repo, git.Repo)
         self.repo.git.config('user.email', 'you@example.com')
         self.repo.git.config('user.name', 'Your Name')
         return self.repo
@@ -59,6 +61,8 @@ def git_commit_new_file(self) -> pathlib.Path:
         with tempfile.NamedTemporaryFile('w', dir=str(self.repo_path), delete=False) as repo_file:
             repo_file.write('spam spam lovely spam\n')
             path = pathlib.Path(repo_file.name)
+        self.assertIsInstance(self.repo, git.Repo)
+        assert isinstance(self.repo, git.Repo), type(self.repo)
         self.repo.index.add([path.name])
         self.repo.index.commit(f'created file {path}')
         _LOG.debug('commited file %s as %s', path, self.repo_head_hexsha)
@@ -68,6 +72,7 @@ def git_commit_new_file(self) -> pathlib.Path:
     def git_modify_file(self, path: pathlib.Path, add: bool = False, commit: bool = False) -> None:
         """Modify an existing file."""
         self.assertIsInstance(self.repo, git.Repo)
+        assert isinstance(self.repo, git.Repo), type(self.repo)
         self.assertIsInstance(path, pathlib.Path)
         self.assertTrue(path.is_file())
         with path.open('a') as repo_file:
diff --git a/boilerplates/setup.py b/boilerplates/setup.py
index 0bfab7a..7eb1c7e 100644
--- a/boilerplates/setup.py
+++ b/boilerplates/setup.py
@@ -290,7 +290,7 @@ class Package:
     install_requires: t.Optional[t.List[str]] = None
     """If None, determined using requirements.txt."""
 
-    extras_require: t.Mapping[str, t.List[str]] = {}
+    extras_require: t.Dict[str, t.List[str]] = {}
     """A dictionary containing entries of type 'some_feature': ['requirement1', 'requirement2']."""
 
     python_requires: t.Optional[str] = None
@@ -383,6 +383,7 @@ def setup(cls) -> None:
             packages=cls.packages, package_dir={'': cls.root_directory},
             include_package_data=True,
             package_data=cls.package_data, exclude_package_data=cls.exclude_package_data,
-            install_requires=cls.install_requires, extras_require=cls.extras_require,
+            install_requires=[] if cls.install_requires is None else cls.install_requires,
+            extras_require=cls.extras_require,
             python_requires=cls.python_requires,
             entry_points=cls.entry_points)
diff --git a/requirements_ci.txt b/requirements_ci.txt
index 87be616..553ca44 100644
--- a/requirements_ci.txt
+++ b/requirements_ci.txt
@@ -3,7 +3,8 @@ boilerplates[setup] ~= 1.2
 codecov ~= 2.1
 coverage ~= 7.2
 flake518 ~= 1.6
-mypy ~= 1.5
+mypy ~= 1.19; python_version < '3.10'
+mypy ~= 2.1; python_version >= '3.10'
 pydocstyle ~= 6.3
 pylint ~= 3.3; python_version < '3.10'
 pylint ~= 4.0; python_version >= '3.10'