diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9096ea1..c94d8e5 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -15,6 +15,7 @@ jobs:
         - python: '3.10'
         - python: '3.11'
         - python: '3.12'
+        - python: '3.13-dev'
     runs-on: ubuntu-latest
     name: Python ${{ matrix.python }}
     steps:
@@ -38,15 +39,24 @@ jobs:
     - name: install package
       run: |
         python -m pip install .[dev,mypy]
+    # Bottle still depends on the old `cgi` module removed in Python 3.13,
+    # thus provide it here.
+    # Avoid the additional error:
+    #     RuntimeError: 'cgi' was slated for removal after Python 3.13 alpha
+    - name: prepare cgi module (Python 3.13)
+      run: |
+        wget https://github.com/python/cpython/raw/3.12/Lib/cgi.py
+        sed --in-place 's/warnings._deprecated(__name__, remove=(3,13))//' cgi.py
+      if: ${{ matrix.python == '3.13-dev' }}
     - name: run tests
       run:
         python -m unittest discover --verbose --start-directory tests
     - name: run flake8
       run:
-        python -m flake8 .
+        python -m flake8 --extend-exclude "cgi.py" .
     - name: run black
       run:
-        black --check --diff .
+        black --check --diff --extend-exclude "cgi.py" .
     - name: run mypy
       run:
         mypy brother_ql_web/ tests/
diff --git a/brother_ql_web/__init__.py b/brother_ql_web/__init__.py
index de9521f..5285cd6 100644
--- a/brother_ql_web/__init__.py
+++ b/brother_ql_web/__init__.py
@@ -20,7 +20,7 @@ def warn(message: str, *args: Any, **kwargs: Any) -> None:
             return
         original_logger(message, *args, **kwargs)
 
-    logging.getLogger("brother_ql.devicedependent").warn = warn  # type: ignore[assignment,method-assign]  # noqa: E501
+    logging.getLogger("brother_ql.devicedependent").warn = warn  # type: ignore[assignment,method-assign,attr-defined,unused-ignore]  # noqa: E501
 
 
 patch_deprecation_warning()
diff --git a/pyproject.toml b/pyproject.toml
index 8b266d5..70339c4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -84,5 +84,5 @@ strict = true
 files = "brother_ql_web,tests"
 
 [tool.codespell]
-skip = "*.min.js*,*.min.css*,venv*"
+skip = "*.min.js*,*.min.css*,venv*,cgi.py"
 ignore-words-list = "assertIn"
diff --git a/stubs/bottle.pyi b/stubs/bottle.pyi
index ec2d5e8..2dd3716 100644
--- a/stubs/bottle.pyi
+++ b/stubs/bottle.pyi
@@ -431,7 +431,7 @@ class ConfigDict(dict):
     def load_config(self, filename, **options): ...
     def load_dict(self, source, namespace: str = ...): ...
     def update(self, *a, **ka) -> None: ...
-    def setdefault(self, key, value): ...
+    def setdefault(self, key: Any, value: Any = None): ...
     def __setitem__(self, key, value): ...
     def __delitem__(self, key) -> None: ...
     def meta_get(self, key, metafield, default: Incomplete | None = ...): ...