diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 44f2e25..02e65af 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -10,7 +10,7 @@ on:
     branches: [ master ]
   # Allow rebuilds via API.
   repository_dispatch:
-    types: rebuild
+    types: [rebuild]
 
 env:
   FORCE_COLOR: "1"
@@ -51,6 +51,14 @@ jobs:
       - name: Run tox targets for ${{ matrix.python-version }}
         run: python -Im tox run -f py$(echo ${{ matrix.python-version }} | tr -d .)
 
+      - name: Run mypy
+        run: python -Im tox run -e mypy
+        if: matrix.python-version == '3.11'
+
+      - name: Run mypy
+        run: python -Im tox run -e mypy
+        if: matrix.python-version == '3.11'
+
       - name: Check MANIFEST.in
         run: python -Im tox run -e manifest
         if: matrix.python-version == '3.11'
@@ -127,6 +135,9 @@ jobs:
       - name: "Create a badge"
         run: interrogate --config pyproject.toml --generate-badge . src tests
         if: runner.os != 'Windows'
+        env:
+          # TODO: set for only macos
+          DYLD_FALLBACK_LIBRARY_PATH: "/opt/homebrew/lib"
 
   docs:
     name: Check docs
diff --git a/README.rst b/README.rst
index 672699c..8a1e304 100644
--- a/README.rst
+++ b/README.rst
@@ -74,11 +74,31 @@ To generate a **PNG file** instead, install ``interrogate`` with the extras ``[p
 **NOTICE:** Additional system libraries/tools may be required in order to generate a PNG file of the coverage badge:
 
 * on Windows, install Visual C++ compiler for Cairo;
-* on macOS, install ``cairo`` and ``libffi`` (with Homebrew for example);
+* on macOS, install ``cairo`` and ``libffi`` (with Homebrew for example - `see note below <#macos-and-cairo>`_);
 * on Linux, install the ``cairo``, ``python3-dev`` and ``libffi-dev`` packages (names may vary depending on distribution).
 
 Refer to the ``cairosvg`` `documentation <https://cairosvg.org/documentation/>`_ for more information.
 
+MacOS and Cairo
+^^^^^^^^^^^^^^^
+
+If you get an error when trying to generate a badge like so:
+
+.. code-block:: console
+
+    OSError: no library called "cairo-2" was found
+    no library called "cairo" was found
+    no library called "libcairo-2" was found
+
+
+Then first try:
+
+.. code-block:: console
+
+    export DYLD_FALLBACK_LIBRARY_PATH=/opt/homebrew/lib
+
+And rerun the command.
+
 Usage
 =====
 
@@ -373,7 +393,7 @@ Configure within your ``pyproject.toml`` (``interrogate`` will automatically det
     ignore-regex = ["^get$", "^mock_.*", ".*BaseClass.*"]
     ext = []
     # possible values: sphinx (default), google
-    style = sphinx
+    style = "sphinx"
     # possible values: 0 (minimal output), 1 (-v), 2 (-vv)
     verbose = 0
     quiet = false
diff --git a/docs/Makefile b/docs/Makefile
index 21a0781..c895b1d 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -10,6 +10,9 @@ ifeq ($(shell which $(SPHINXBUILD) >/dev/null 2>&1; echo $$?), 1)
 $(error The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed, then set the SPHINXBUILD environment variable to point to the full path of the '$(SPHINXBUILD)' executable. Alternatively you can add the directory with the executable to your PATH. If you don't have Sphinx installed, grab it from http://sphinx-doc.org/)
 endif
 
+# Internal variables
+ALLSPHINXOPTS   = -d $(BUILDDIR)/doctrees $(SPHINXOPTS) .
+
 .PHONY: help clean html livehtml linkcheck
 
 help:
diff --git a/docs/changelog.rst b/docs/changelog.rst
index 24f7456..07dfb94 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -1,6 +1,14 @@
 Changelog
 =========
 
+1.8.0 (UNRELEASED)
+------------------
+
+Added
+^^^^^
+
+* Finally added type hints
+
 .. short-log
 
 1.7.0 (2024-04-07)
diff --git a/pyproject.toml b/pyproject.toml
index d0a57dd..eba8295 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,11 +29,8 @@ fail_under = 95
 line-length = 79
 
 [tool.isort]
-atomic=true
-force_single_line=true
 lines_after_imports=2
 lines_between_types=1
-use_parentheses=true
 known_first_party="interrogate"
 known_third_party=["attr", "click", "py", "pytest", "setuptools", "tabulate"]
 
@@ -53,3 +50,8 @@ quiet = false
 whitelist-regex = []
 ignore-regex = []
 color = true
+
+[tool.mypy]
+strict = true
+pretty = true
+ignore_missing_imports = true
diff --git a/setup.py b/setup.py
index 8a42f4f..aeeb025 100644
--- a/setup.py
+++ b/setup.py
@@ -5,8 +5,7 @@
 import os
 import re
 
-from setuptools import find_packages
-from setuptools import setup
+from setuptools import find_packages, setup
 
 
 HERE = os.path.abspath(os.path.dirname(__file__))
@@ -80,11 +79,13 @@ def find_meta(meta):
     "png": ["cairosvg"],
     "docs": ["sphinx", "sphinx-autobuild"],
     "tests": ["pytest", "pytest-cov", "pytest-mock", "coverage[toml]"],
+    "typing": ["mypy", "types-tabulate"],
 }
 EXTRAS_REQUIRE["dev"] = (
     EXTRAS_REQUIRE["png"]
     + EXTRAS_REQUIRE["docs"]
     + EXTRAS_REQUIRE["tests"]
+    + EXTRAS_REQUIRE["typing"]
     + ["wheel", "pre-commit"]
 )
 URL = find_meta("uri")
diff --git a/src/interrogate/__init__.py b/src/interrogate/__init__.py
index 5b846c2..1d4ee72 100644
--- a/src/interrogate/__init__.py
+++ b/src/interrogate/__init__.py
@@ -1,4 +1,4 @@
-# Copyright 2020-2021 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Explain yourself! Interrogate a codebase for docstring coverage."""
 __author__ = "Lynn Root"
 __version__ = "1.7.0"
diff --git a/src/interrogate/__main__.py b/src/interrogate/__main__.py
index 2c58f85..52b1d12 100644
--- a/src/interrogate/__main__.py
+++ b/src/interrogate/__main__.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """interrogate entrypoint"""
 
 from interrogate import cli
diff --git a/src/interrogate/badge_gen.py b/src/interrogate/badge_gen.py
index 763613d..8a9479c 100644
--- a/src/interrogate/badge_gen.py
+++ b/src/interrogate/badge_gen.py
@@ -1,13 +1,15 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Module for generating an SVG badge.
 
 Inspired by `coverage-badge <https://github.com/dbrgn/coverage-badge>`_.
 """
+from __future__ import annotations
 
 import os
 import sys
 
 from importlib import resources
+from typing import Union
 from xml.dom import minidom
 
 
@@ -16,9 +18,13 @@
 except ImportError:  # pragma: no cover
     cairosvg = None
 
+from interrogate.coverage import InterrogateResults
 
-DEFAULT_FILENAME = "interrogate_badge"
-COLORS = {
+
+NumberType = Union[int, float]
+
+DEFAULT_FILENAME: str = "interrogate_badge"
+COLORS: dict[str, str] = {
     "brightgreen": "#4c1",
     "green": "#97CA00",
     "yellowgreen": "#a4a61d",
@@ -28,7 +34,7 @@
     "lightgrey": "#9f9f9f",
 }
 
-COLOR_RANGES = [
+COLOR_RANGES: list[tuple[int, str]] = [
     (95, "brightgreen"),
     (90, "green"),
     (75, "yellowgreen"),
@@ -36,11 +42,13 @@
     (40, "orange"),
     (0, "red"),
 ]
-SUPPORTED_OUTPUT_FORMATS = ["svg", "png"]
+SUPPORTED_OUTPUT_FORMATS: list[str] = ["svg", "png"]
 # depending on the character length of the result (e.g. 100, 99.9, 9.9)
 # a few values in the svg template need to adjust so it's readable.
 # Tuple of values: (svg_width, rect_width, text_x, text_length)
-SVG_WIDTH_VALUES = {
+SVG_WIDTH_VALUES: dict[
+    str, dict[str, tuple[int, int, NumberType, NumberType]]
+] = {
     # integer
     "100": {
         "plastic": (135, 43, 1140, 330),
@@ -71,7 +79,9 @@
 }
 
 
-def save_badge(badge, output, output_format=None):
+def save_badge(
+    badge: str, output: str, output_format: str | None = None
+) -> str:
     """Save badge to the specified path.
 
     .. versionadded:: 1.4.0 new ``output_format`` keyword argument
@@ -116,7 +126,9 @@ def save_badge(badge, output, output_format=None):
     return output
 
 
-def _get_badge_measurements(result, style):
+def _get_badge_measurements(
+    result: float, style: str
+) -> dict[str, NumberType]:
     """Lookup templated style values based on result number."""
     if result == 100:
         width_values = SVG_WIDTH_VALUES["100"]
@@ -133,7 +145,7 @@ def _get_badge_measurements(result, style):
     }
 
 
-def _format_result(result):
+def _format_result(result: float) -> str:
     """Format result into string for templating."""
     # do not include decimal if it's 100
     if result == 100:
@@ -141,7 +153,7 @@ def _format_result(result):
     return f"{result:.1f}"
 
 
-def get_badge(result, color, style=None):
+def get_badge(result: float, color: str, style: str | None = None) -> str:
     """Generate an SVG from template.
 
     :param float result: coverage % result.
@@ -154,9 +166,9 @@ def get_badge(result, color, style=None):
         style = "flat-square-modified"
     template_file = f"{style}-style.svg"
     badge_template_values = _get_badge_measurements(result, style)
-    result = _format_result(result)
-    badge_template_values["result"] = result
-    badge_template_values["color"] = color
+    formatted_result = _format_result(result)
+    badge_template_values["result"] = formatted_result  # type: ignore
+    badge_template_values["color"] = color  # type: ignore
 
     if sys.version_info >= (3, 9):
         tmpl = (
@@ -171,7 +183,7 @@ def get_badge(result, color, style=None):
     return tmpl
 
 
-def should_generate_badge(output, color, result):
+def should_generate_badge(output: str, color: str, result: float) -> bool:
     """Detect if existing badge needs updating.
 
     This is to help avoid unnecessary newline updates. See
@@ -186,8 +198,8 @@ def should_generate_badge(output, color, result):
         logo doesn't exist.
 
     :param str output: path to output badge file
-    :param float result: coverage % result.
     :param str color: color of badge.
+    :param float result: coverage % result.
     :return: Whether or not the badge SVG file should be generated.
     :rtype: bool
     """
@@ -228,13 +240,13 @@ def should_generate_badge(output, color, result):
         for t in texts
         if t.hasAttribute("data-interrogate")
     ]
-    result = f"{result:.1f}%"
-    if result in current_results:
+    formatted_result = f"{result:.1f}%"
+    if formatted_result in current_results:
         return False
     return True
 
 
-def get_color(result):
+def get_color(result: float) -> str:
     """Get color for current doc coverage percent.
 
     :param float result: coverage % result
@@ -247,7 +259,12 @@ def get_color(result):
     return COLORS["lightgrey"]
 
 
-def create(output, result, output_format=None, output_style=None):
+def create(
+    output: str,
+    result: InterrogateResults,
+    output_format: str | None = None,
+    output_style: str | None = None,
+) -> str:
     """Create a status badge.
 
     The badge file will only be written if it doesn't exist, or if the
@@ -263,6 +280,11 @@ def create(output, result, output_format=None, output_style=None):
     :param str output: path to output badge file.
     :param coverage.InterrogateResults result: results of coverage
         interrogation.
+    :param str output_format: output format of the badge. Options: "svg", "png".
+        Default: "svg"
+    :param str output_style: badge styling. Options: "plastic", "social",
+        "flat", "flat-square", "flat-square-modified", "for-the-badge".
+        Default: "flat-square-modified"
     :return: path to output badge file.
     :rtype: str
     """
diff --git a/src/interrogate/cli.py b/src/interrogate/cli.py
index ec71370..86b9084 100644
--- a/src/interrogate/cli.py
+++ b/src/interrogate/cli.py
@@ -1,17 +1,18 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """CLI entrypoint into `interrogate`."""
 
 import os
 import sys
 
+from typing import List, Optional, Pattern, Tuple, Union
+
 import click
 import colorama
 
 from interrogate import __version__ as version
 from interrogate import badge_gen
-from interrogate import config
-from interrogate import coverage
-from interrogate import utils
+from interrogate import config as int_config
+from interrogate import coverage, utils
 
 
 @click.command()
@@ -101,20 +102,20 @@
     help="Ignore module-level docstrings.",
 )
 @click.option(
-    "-n",
-    "--ignore-nested-functions",
+    "-C",
+    "--ignore-nested-classes",
     is_flag=True,
     default=False,
     show_default=True,
-    help="Ignore nested functions and methods.",
+    help="Ignore nested classes.",
 )
 @click.option(
-    "-C",
-    "--ignore-nested-classes",
+    "-n",
+    "--ignore-nested-functions",
     is_flag=True,
     default=False,
     show_default=True,
-    help="Ignore nested classes.",
+    help="Ignore nested functions and methods.",
 )
 @click.option(
     "-O",
@@ -182,7 +183,7 @@
     default=(),
     multiple=True,
     metavar="STR",
-    type=click.Choice(["pyi"], case_sensitive=False),
+    type=click.Choice(["pyi", "ipynb"], case_sensitive=False),
     help=(
         "Include Python-like files with the given extension "
         "(supported: ``pyi``). Multiple ``--ext`` invocations supported. "
@@ -308,11 +309,38 @@
         exists=False, file_okay=True, dir_okay=False, readable=True
     ),
     is_eager=True,
-    callback=config.read_config_file,
+    callback=int_config.read_config_file,
     help="Read configuration from `pyproject.toml` or `setup.cfg`.",
 )
-@click.pass_context
-def main(ctx, paths, **kwargs):
+def main(
+    paths: Optional[List[str]],
+    verbose: int,
+    quiet: bool,
+    fail_under: Union[int, float],
+    exclude: Tuple[str],
+    ignore_init_method: bool,
+    ignore_init_module: bool,
+    ignore_magic: bool,
+    ignore_module: bool,
+    ignore_nested_classes: bool,
+    ignore_nested_functions: bool,
+    ignore_overloaded_functions: bool,
+    ignore_private: bool,
+    ignore_property_decorators: bool,
+    ignore_setters: bool,
+    ignore_semiprivate: bool,
+    ignore_regex: Optional[List[Pattern[str]]],
+    ext: Tuple[str],
+    whitelist_regex: Optional[List[Pattern[str]]],
+    style: str,
+    output: Optional[str],
+    color: bool,
+    omit_covered_files: bool,
+    generate_badge: Optional[str],
+    badge_format: Optional[str],
+    badge_style: Optional[str],
+    config: Optional[str],
+) -> None:
     """Measure and report on documentation coverage in Python modules.
 
     \f
@@ -342,18 +370,17 @@ def main(ctx, paths, **kwargs):
     .. versionchanged:: 1.7.0 include property deleters when ignoring all
         property decorators (--ignore-property-decorators)
     """
-    gen_badge = kwargs["generate_badge"]
-    if kwargs["badge_format"] is not None and gen_badge is None:
+    if badge_format is not None and generate_badge is None:
         raise click.BadParameter(
             "The `--badge-format` option must be used along with the `-g/"
             "--generate-badge option."
         )
-    if kwargs["badge_style"] is not None and gen_badge is None:
+    if badge_style is not None and generate_badge is None:
         raise click.BadParameter(
             "The `--badge-style` option must be used along with the `-g/"
             "--generate-badge option."
         )
-    if kwargs["style"] == "google" and kwargs["ignore_init_method"]:
+    if style == "google" and ignore_init_method:
         raise click.BadOptionUsage(
             option_name="style",
             message=(
@@ -362,60 +389,57 @@ def main(ctx, paths, **kwargs):
             ),
         )
     if not paths:
-        paths = (os.path.abspath(os.getcwd()),)
+        paths = [os.path.abspath(os.getcwd())]
 
     # NOTE: this will need to be fixed if we want to start supporting
     #       --whitelist-regex on filenames. This otherwise assumes you
     #       want to ignore module-level docs when only white listing
     #       items (visit.py will also need to be addressed since white/
     #       black listing only looks at classes & funcs, not modules).
-    if kwargs["whitelist_regex"]:
-        kwargs["ignore_module"] = True
+    if whitelist_regex:
+        ignore_module = True
 
-    conf = config.InterrogateConfig(
-        color=kwargs["color"],
-        docstring_style=kwargs["style"],
-        fail_under=kwargs["fail_under"],
-        ignore_regex=kwargs["ignore_regex"],
-        ignore_magic=kwargs["ignore_magic"],
-        ignore_module=kwargs["ignore_module"],
-        ignore_private=kwargs["ignore_private"],
-        ignore_semiprivate=kwargs["ignore_semiprivate"],
-        ignore_init_method=kwargs["ignore_init_method"],
-        ignore_init_module=kwargs["ignore_init_module"],
-        ignore_nested_classes=kwargs["ignore_nested_classes"],
-        ignore_nested_functions=kwargs["ignore_nested_functions"],
-        ignore_overloaded_functions=kwargs["ignore_overloaded_functions"],
-        ignore_property_setters=kwargs["ignore_setters"],
-        ignore_property_decorators=kwargs["ignore_property_decorators"],
-        include_regex=kwargs["whitelist_regex"],
-        omit_covered_files=kwargs["omit_covered_files"],
+    conf = int_config.InterrogateConfig(
+        color=color,
+        docstring_style=style,
+        fail_under=fail_under,
+        ignore_regex=ignore_regex,
+        ignore_magic=ignore_magic,
+        ignore_module=ignore_module,
+        ignore_private=ignore_private,
+        ignore_semiprivate=ignore_semiprivate,
+        ignore_init_method=ignore_init_method,
+        ignore_init_module=ignore_init_module,
+        ignore_nested_classes=ignore_nested_classes,
+        ignore_nested_functions=ignore_nested_functions,
+        ignore_overloaded_functions=ignore_overloaded_functions,
+        ignore_property_setters=ignore_setters,
+        ignore_property_decorators=ignore_property_decorators,
+        include_regex=whitelist_regex,
+        omit_covered_files=omit_covered_files,
     )
     interrogate_coverage = coverage.InterrogateCoverage(
         paths=paths,
         conf=conf,
-        excluded=kwargs["exclude"],
-        extensions=kwargs["ext"],
+        excluded=exclude,
+        extensions=ext,
     )
     results = interrogate_coverage.get_coverage()
 
-    is_quiet = kwargs["quiet"]
-    if not is_quiet:
+    if not quiet:
         colorama.init()  # needed for Windows
-        interrogate_coverage.print_results(
-            results, kwargs["output"], kwargs["verbose"]
-        )
+        interrogate_coverage.print_results(results, output, verbose)
 
-    if gen_badge is not None:
-        badge_format = kwargs["badge_format"]
-        badge_style = kwargs["badge_style"]
+    if generate_badge is not None:
+        badge_format = badge_format
+        badge_style = badge_style
         output_path = badge_gen.create(
-            gen_badge,
+            generate_badge,
             results,
             output_format=badge_format,
             output_style=badge_style,
         )
-        if not is_quiet:
+        if not quiet:
             click.echo(f"Generated badge to {output_path}")
 
     sys.exit(results.ret_code)
diff --git a/src/interrogate/config.py b/src/interrogate/config.py
index d3fdafa..13dc0ac 100644
--- a/src/interrogate/config.py
+++ b/src/interrogate/config.py
@@ -1,12 +1,18 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """
 Configuration-related helpers.
 """
 # Adapted from Black https://github.com/psf/black/blob/master/black.py.
 
+from __future__ import annotations
+
 import configparser
 import os
 import pathlib
+import re
+
+from collections.abc import Sequence
+from typing import Any
 
 import attr
 import click
@@ -15,7 +21,7 @@
 try:
     import tomllib
 except ImportError:
-    import tomli as tomllib
+    import tomli as tomllib  # type: ignore
 
 
 # TODO: idea: break out InterrogateConfig into two classes: one for
@@ -52,26 +58,26 @@ class InterrogateConfig:
 
     VALID_STYLES = ("sphinx", "google")
 
-    color = attr.ib(default=False)
-    docstring_style = attr.ib(default="sphinx")
-    fail_under = attr.ib(default=80.0)
-    ignore_regex = attr.ib(default=False)
-    ignore_magic = attr.ib(default=False)
-    ignore_module = attr.ib(default=False)
-    ignore_private = attr.ib(default=False)
-    ignore_semiprivate = attr.ib(default=False)
-    ignore_init_method = attr.ib(default=False)
-    ignore_init_module = attr.ib(default=False)
-    ignore_nested_classes = attr.ib(default=False)
-    ignore_nested_functions = attr.ib(default=False)
-    ignore_property_setters = attr.ib(default=False)
-    ignore_property_decorators = attr.ib(default=False)
-    ignore_overloaded_functions = attr.ib(default=False)
-    include_regex = attr.ib(default=False)
-    omit_covered_files = attr.ib(default=False)
+    color: bool = attr.ib(default=False)
+    docstring_style: str = attr.ib(default="sphinx")
+    fail_under: float = attr.ib(default=80.0)
+    ignore_regex: list[re.Pattern[str]] | None = attr.ib(default=None)
+    ignore_magic: bool = attr.ib(default=False)
+    ignore_module: bool = attr.ib(default=False)
+    ignore_private: bool = attr.ib(default=False)
+    ignore_semiprivate: bool = attr.ib(default=False)
+    ignore_init_method: bool = attr.ib(default=False)
+    ignore_init_module: bool = attr.ib(default=False)
+    ignore_nested_classes: bool = attr.ib(default=False)
+    ignore_nested_functions: bool = attr.ib(default=False)
+    ignore_property_setters: bool = attr.ib(default=False)
+    ignore_property_decorators: bool = attr.ib(default=False)
+    ignore_overloaded_functions: bool = attr.ib(default=False)
+    include_regex: list[re.Pattern[str]] | None = attr.ib(default=None)
+    omit_covered_files: bool = attr.ib(default=False)
 
     @docstring_style.validator
-    def _check_style(self, attribute, value):
+    def _check_style(self, attribute: str, value: str) -> None:
         """Validate selected choice for docstring style"""
         if value not in self.VALID_STYLES:
             raise ValueError(
@@ -80,7 +86,7 @@ def _check_style(self, attribute, value):
             )
 
 
-def find_project_root(srcs):
+def find_project_root(srcs: Sequence[str]) -> pathlib.Path:
     """Return a directory containing .git, .hg, or pyproject.toml.
     That directory can be one of the directories passed in `srcs` or their
     common parent.
@@ -108,7 +114,7 @@ def find_project_root(srcs):
     return directory
 
 
-def find_project_config(path_search_start):
+def find_project_config(path_search_start: Sequence[str]) -> str | None:
     """Find the absolute filepath to a pyproject.toml if it exists."""
     project_root = find_project_root(path_search_start)
     pyproject_toml = project_root / "pyproject.toml"
@@ -119,7 +125,7 @@ def find_project_config(path_search_start):
     return str(setup_cfg) if setup_cfg.is_file() else None
 
 
-def parse_pyproject_toml(path_config):
+def parse_pyproject_toml(path_config: str) -> dict[str, Any]:
     """Parse ``pyproject.toml`` file and return relevant parts for Interrogate.
 
     :param str path_config: Path to ``pyproject.toml`` file.
@@ -136,7 +142,7 @@ def parse_pyproject_toml(path_config):
     }
 
 
-def sanitize_list_values(value):
+def sanitize_list_values(value: str) -> list[str | None]:
     """Parse a string of list items to a Python list.
 
     This is super hacky...
@@ -159,7 +165,7 @@ def sanitize_list_values(value):
     return [v.strip('"') for v in raw_values]
 
 
-def parse_setup_cfg(path_config):
+def parse_setup_cfg(path_config: str) -> dict[str, Any] | None:
     """Parse ``setup.cfg`` file and return relevant parts for Interrogate.
 
     This is super hacky...
@@ -185,15 +191,17 @@ def parse_setup_cfg(path_config):
     }
     for k, v in config.items():
         if k in keys_for_list_values:
-            config[k] = sanitize_list_values(v)
+            config[k] = sanitize_list_values(v)  # type: ignore
         elif v.lower() == "false":
-            config[k] = False
+            config[k] = False  # type: ignore
         elif v.lower() == "true":
-            config[k] = True
+            config[k] = True  # type: ignore
     return config
 
 
-def read_config_file(ctx, param, value):
+def read_config_file(
+    ctx: click.Context, param: click.Parameter, value: str | None
+) -> str | None:
     """Inject config from ``pyproject.toml`` or ``setup.py`` into ``ctx``.
 
     These override option defaults, but still respect option values
diff --git a/src/interrogate/coverage.py b/src/interrogate/coverage.py
index ebf4bf7..4c1226b 100644
--- a/src/interrogate/coverage.py
+++ b/src/interrogate/coverage.py
@@ -1,20 +1,21 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Measure and report on documentation coverage in Python modules."""
+
+from __future__ import annotations
+
 import ast
 import decimal
+import fnmatch
 import os
-import pathlib
 import sys
 
-from fnmatch import fnmatch
+from typing import Final, Iterator
 
 import attr
 import click
 import tabulate
 
-from interrogate import config
-from interrogate import utils
-from interrogate import visit
+from interrogate import config, utils, visit
 
 
 tabulate.PRESERVE_WHITESPACE = True
@@ -30,12 +31,12 @@ class BaseInterrogateResult:
     :attr int missing: number of objects not covered by docstrings.
     """
 
-    total = attr.ib(init=False, default=0)
-    covered = attr.ib(init=False, default=0)
-    missing = attr.ib(init=False, default=0)
+    total: int = attr.ib(init=False, default=0)
+    covered: int = attr.ib(init=False, default=0)
+    missing: int = attr.ib(init=False, default=0)
 
     @property
-    def perc_covered(self):
+    def perc_covered(self) -> float:
         """Percentage of node covered.
 
         .. versionchanged:: 1.3.2
@@ -57,15 +58,14 @@ class InterrogateFileResult(BaseInterrogateResult):
 
     :param str filename: filename associated with the coverage result.
     :param bool ignore_module: whether or not to ignore this file/module.
-    :param visit.CoverageVisitor visitor: coverage visitor instance
-        that assessed docstring coverage of file.
+    :param list[visit.CovNode] nodes: visited AST nodes.
     """
 
-    filename = attr.ib(default=None)
-    ignore_module = attr.ib(default=False)
-    nodes = attr.ib(repr=False, default=None)
+    filename: str = attr.ib(default=None)
+    ignore_module: bool = attr.ib(default=False)
+    nodes: list[visit.CovNode] = attr.ib(repr=False, default=None)
 
-    def combine(self):
+    def combine(self) -> None:
         """Tally results from each AST node visited."""
         for node in self.nodes:
             if node.node_type == "Module":
@@ -84,14 +84,16 @@ class InterrogateResults(BaseInterrogateResult):
 
     :attr int ret_code: return code of program (``0`` for success, ``1``
         for fail).
-    :attr list(InterrogateFileResults) file_results: list of file
+    :attr list(InterrogateFileResult) file_results: list of file
         results associated with this program run.
     """
 
-    ret_code = attr.ib(init=False, default=0, repr=False)
-    file_results = attr.ib(init=False, default=None, repr=False)
+    ret_code: int = attr.ib(init=False, default=0, repr=False)
+    file_results: list[InterrogateFileResult] = attr.ib(
+        init=False, default=None, repr=False
+    )
 
-    def combine(self):
+    def combine(self) -> None:
         """Tally results from each file."""
         for result in self.file_results:
             self.covered += result.covered
@@ -106,30 +108,40 @@ class InterrogateCoverage:
     :param config.InterrogateConfig conf: interrogation configuration.
     :param tuple(str) excluded: tuple of files and directories to exclude
         in assessing coverage.
+    :param list[str] extensions: additional file extensions to interrogate.
     """
 
-    COMMON_EXCLUDE = [".tox", ".venv", "venv", ".git", ".hg"]
-    VALID_EXT = [".py", ".pyi"]  # someday in the future: .ipynb
-
-    def __init__(self, paths, conf=None, excluded=None, extensions=None):
+    COMMON_EXCLUDE: Final[list[str]] = [".tox", ".venv", "venv", ".git", ".hg"]
+    VALID_EXT: Final[list[str]] = [
+        ".py",
+        ".pyi",
+    ]  # someday in the future: .ipynb
+
+    def __init__(
+        self,
+        paths: list[str],
+        conf: config.InterrogateConfig | None = None,
+        excluded: tuple[str] | None = None,
+        extensions: tuple[str] | None = None,
+    ):
         self.paths = paths
         self.extensions = set(extensions or set())
         self.extensions.add(".py")
         self.config = conf or config.InterrogateConfig()
         self.excluded = excluded or ()
-        self.common_base = pathlib.Path("/")
-        self.output_formatter = None
+        self.common_base = ""
         self._add_common_exclude()
         self.skipped_file_count = 0
+        self.output_formatter: utils.OutputFormatter
 
-    def _add_common_exclude(self):
+    def _add_common_exclude(self) -> None:
         """Ignore common directories by default"""
         for path in self.paths:
-            self.excluded = self.excluded + tuple(
+            self.excluded = self.excluded + tuple(  # type: ignore
                 os.path.join(path, i) for i in self.COMMON_EXCLUDE
             )
 
-    def _filter_files(self, files):
+    def _filter_files(self, files: list[str]) -> Iterator[str]:
         """Filter files that are explicitly excluded."""
         for f in files:
             has_valid_ext = any([f.endswith(ext) for ext in self.extensions])
@@ -139,11 +151,11 @@ def _filter_files(self, files):
                 basename = os.path.basename(f)
                 if basename == "__init__.py":
                     continue
-            if any(fnmatch(f, exc + "*") for exc in self.excluded):
+            if any(fnmatch.fnmatch(f, exc + "*") for exc in self.excluded):
                 continue
             yield f
 
-    def get_filenames_from_paths(self):
+    def get_filenames_from_paths(self) -> list[str]:
         """Find all files to measure for docstring coverage."""
         filenames = []
         for path in self.paths:
@@ -177,7 +189,7 @@ def get_filenames_from_paths(self):
         self.common_base = utils.get_common_base(filenames)
         return filenames
 
-    def _filter_nodes(self, nodes):
+    def _filter_nodes(self, nodes: list[visit.CovNode]) -> list[visit.CovNode]:
         """Remove empty modules when ignoring modules."""
         is_empty = 1 == len(nodes)
         if is_empty and self.config.ignore_module:
@@ -203,7 +215,9 @@ def _filter_nodes(self, nodes):
             filtered.insert(0, module_node)
         return filtered
 
-    def _filter_inner_nested(self, nodes):
+    def _filter_inner_nested(
+        self, nodes: list[visit.CovNode]
+    ) -> list[visit.CovNode]:
         """Filter out children of ignored nested funcs/classes."""
         nested_cls = [n for n in nodes if n.is_nested_cls]
         inner_nested_nodes = [n for n in nodes if n.parent in nested_cls]
@@ -212,7 +226,7 @@ def _filter_inner_nested(self, nodes):
         filtered_nodes = [n for n in filtered_nodes if n not in nested_cls]
         return filtered_nodes
 
-    def _set_google_style(self, nodes):
+    def _set_google_style(self, nodes: list[visit.CovNode]) -> None:
         """Apply Google-style docstrings for class coverage.
 
         Update coverage of a class node if its `__init__` method has a
@@ -224,12 +238,14 @@ def _set_google_style(self, nodes):
         """
         for node in nodes:
             if node.node_type == "FunctionDef" and node.name == "__init__":
-                if not node.covered and node.parent.covered:
+                if not node.covered and node.parent.covered:  # type: ignore
                     setattr(node, "covered", True)
-                elif node.covered and not node.parent.covered:
+                elif node.covered and not node.parent.covered:  # type: ignore
                     setattr(node.parent, "covered", True)
 
-    def _get_file_coverage(self, filename):
+    def _get_file_coverage(
+        self, filename: str
+    ) -> InterrogateFileResult | None:
         """Get coverage results for a particular file."""
         with open(filename, encoding="utf-8") as f:
             source_tree = f.read()
@@ -240,7 +256,7 @@ def _get_file_coverage(self, filename):
 
         filtered_nodes = self._filter_nodes(visitor.nodes)
         if len(filtered_nodes) == 0:
-            return
+            return None
 
         if self.config.ignore_nested_functions:
             filtered_nodes = [
@@ -260,7 +276,7 @@ def _get_file_coverage(self, filename):
         results.combine()
         return results
 
-    def _get_coverage(self, filenames):
+    def _get_coverage(self, filenames: list[str]) -> InterrogateResults:
         """Get coverage results."""
         results = InterrogateResults()
         file_results = []
@@ -273,19 +289,20 @@ def _get_coverage(self, filenames):
         results.combine()
 
         fail_under_str = str(self.config.fail_under)
-        round_to = -decimal.Decimal(fail_under_str).as_tuple().exponent
+        fail_under_dec = decimal.Decimal(fail_under_str)
+        round_to = -fail_under_dec.as_tuple().exponent  # type: ignore
 
         if self.config.fail_under > round(results.perc_covered, round_to):
             results.ret_code = 1
 
         return results
 
-    def get_coverage(self):
+    def get_coverage(self) -> InterrogateResults:
         """Get coverage results from files."""
         filenames = self.get_filenames_from_paths()
         return self._get_coverage(filenames)
 
-    def _get_filename(self, filename):
+    def _get_filename(self, filename: str) -> str:
         """Get filename for output information.
 
         If only one file is being interrogated, then ``self.common_base``
@@ -296,7 +313,9 @@ def _get_filename(self, filename):
             return os.path.basename(filename)
         return filename[len(self.common_base) + 1 :]
 
-    def _get_detailed_row(self, node, filename):
+    def _get_detailed_row(
+        self, node: visit.CovNode, filename: str
+    ) -> list[str]:
         """Generate a row of data for the detailed view."""
         filename = self._get_filename(filename)
 
@@ -313,14 +332,16 @@ def _get_detailed_row(self, node, filename):
         status = "MISSED" if not node.covered else "COVERED"
         return [name, status]
 
-    def _create_detailed_table(self, combined_results):
+    def _create_detailed_table(
+        self, combined_results: InterrogateResults
+    ) -> list[list[str]]:
         """Generate table for the detailed view.
 
         The detailed view shows coverage of each module, class, and
         function/method.
         """
 
-        def _sort_nodes(x):
+        def _sort_nodes(x: visit.CovNode) -> int:
             """Sort nodes by line number."""
             lineno = getattr(x, "lineno", 0)
             # lineno is "None" if module is empty
@@ -347,7 +368,7 @@ def _sort_nodes(x):
             verbose_tbl.append(self.output_formatter.TABLE_SEPARATOR)
         return verbose_tbl
 
-    def _print_detailed_table(self, results):
+    def _print_detailed_table(self, results: InterrogateResults) -> None:
         """Print detailed table to the given output stream."""
         detailed_table = self._create_detailed_table(results)
 
@@ -370,7 +391,9 @@ def _print_detailed_table(self, results):
         self.output_formatter.tw.line(to_print)
         self.output_formatter.tw.line()
 
-    def _create_summary_table(self, combined_results):
+    def _create_summary_table(
+        self, combined_results: InterrogateResults
+    ) -> list[list[str]]:
         """Generate table for the summary view.
 
         The summary view shows coverage for an overall file.
@@ -390,9 +413,9 @@ def _create_summary_table(self, combined_results):
             perc_covered = f"{file_result.perc_covered:.0f}%"
             row = [
                 filename,
-                file_result.total,
-                file_result.missing,
-                file_result.covered,
+                str(file_result.total),
+                str(file_result.missing),
+                str(file_result.covered),
                 perc_covered,
             ]
             table.append(row)
@@ -405,15 +428,15 @@ def _create_summary_table(self, combined_results):
         total_perc_covered = f"{combined_results.perc_covered:.1f}%"
         total_row = [
             "TOTAL",
-            combined_results.total,
-            combined_results.missing,
-            combined_results.covered,
+            str(combined_results.total),
+            str(combined_results.missing),
+            str(combined_results.covered),
             total_perc_covered,
         ]
         table.append(total_row)
         return table
 
-    def _print_summary_table(self, results):
+    def _print_summary_table(self, results: InterrogateResults) -> None:
         """Print summary table to the given output stream."""
         summary_table = self._create_summary_table(results)
         self.output_formatter.tw.sep(
@@ -431,7 +454,7 @@ def _print_summary_table(self, results):
         self.output_formatter.tw.line(to_print)
 
     @staticmethod
-    def _sort_results(results):
+    def _sort_results(results: InterrogateResults) -> InterrogateResults:
         """Sort results by filename, directories first"""
         all_filenames_map = {r.filename: r for r in results.file_results}
         all_dirs = sorted(
@@ -459,7 +482,7 @@ def _sort_results(results):
         results.file_results = sorted_res
         return results
 
-    def _get_header_base(self):
+    def _get_header_base(self) -> str:
         """Get common base directory for header of verbose output."""
         base = self.common_base
         if os.path.isfile(base):
@@ -468,7 +491,7 @@ def _get_header_base(self):
             return base + "\\"
         return base + "/"
 
-    def _print_omitted_file_count(self, results):
+    def _print_omitted_file_count(self, results: InterrogateResults) -> None:
         """Print # of files omitted due to 100% coverage and --omit-covered.
 
         :param InterrogateResults results: results of docstring coverage
@@ -499,7 +522,9 @@ def _print_omitted_file_count(self, results):
         )
         self.output_formatter.tw.line(to_print)
 
-    def print_results(self, results, output, verbosity):
+    def print_results(
+        self, results: InterrogateResults, output: str | None, verbosity: int
+    ) -> None:
         """Print results to a given output stream.
 
         :param InterrogateResults results: results of docstring coverage
diff --git a/src/interrogate/utils.py b/src/interrogate/utils.py
index f96dc65..d8cb942 100644
--- a/src/interrogate/utils.py
+++ b/src/interrogate/utils.py
@@ -1,6 +1,8 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Collection of general helper functions."""
 
+from __future__ import annotations
+
 import contextlib
 import functools
 import os
@@ -9,16 +11,23 @@
 import shutil
 import sys
 
+from typing import IO, Any, Final, Iterator, Sequence
+
 import colorama
 import tabulate
 
+from click import Context, Parameter
 from py import io as py_io
 
+from interrogate.config import InterrogateConfig
+
 
-IS_WINDOWS = sys.platform == "win32"
+IS_WINDOWS: Final[bool] = sys.platform == "win32"
 
 
-def parse_regex(ctx, param, values):
+def parse_regex(
+    ctx: Context, param: Parameter, values: list[str]
+) -> list[re.Pattern[str]] | None:
     """Compile a regex if given.
 
     :param click.Context ctx: click command context.
@@ -32,12 +41,14 @@ def parse_regex(ctx, param, values):
         ``list`` of ``str``s.
     """
     if not values:
-        return
+        return None
     return [re.compile(v) for v in values]
 
 
 @contextlib.contextmanager
-def smart_open(filename=None, fmode=None):
+def smart_open(
+    filename: str | None = None, fmode: str = "w"
+) -> Iterator[IO[Any]]:
     """Context manager to handle both stdout & files in the same manner.
 
     :param filename: Filename to open.
@@ -57,7 +68,7 @@ def smart_open(filename=None, fmode=None):
             fh.close()
 
 
-def get_common_base(files):
+def get_common_base(files: Sequence[str | pathlib.Path]) -> str:
     """Find the common parent base path for a list of files.
 
     For example, ``["/usr/src/app", "/usr/src/tests", "/usr/src/app2"]``
@@ -83,11 +94,11 @@ class OutputFormatter:
     TERMINAL_WIDTH, _ = shutil.get_terminal_size((80, 20))
     TABLE_SEPARATOR = ["---"]
 
-    def __init__(self, config, file=None):
+    def __init__(self, config: InterrogateConfig, file: IO[Any] | None = None):
         self.config = config
         self.tw = py_io.TerminalWriter(file=file)
 
-    def should_markup(self):
+    def should_markup(self) -> bool:
         """Return whether or not color markup should be added to output."""
         if self.config.color is False:
             return False
@@ -102,7 +113,7 @@ def should_markup(self):
 
         return True
 
-    def set_detailed_markup(self, padded_cells):
+    def set_detailed_markup(self, padded_cells: list[str]) -> list[str]:
         """Add markup specific to the detailed output section."""
         if not self.should_markup():
             return padded_cells
@@ -126,7 +137,7 @@ def set_detailed_markup(self, padded_cells):
 
         return marked_up_padded_cells
 
-    def set_summary_markup(self, padded_cells):
+    def set_summary_markup(self, padded_cells: list[str]) -> list[str]:
         """Add markup specific to the summary output section."""
         if not self.should_markup():
             return padded_cells
@@ -156,8 +167,12 @@ def set_summary_markup(self, padded_cells):
         return marked_up_padded_cells
 
     def _interrogate_line_formatter(
-        self, padded_cells, colwidths, colaligns, table_type
-    ):
+        self,
+        padded_cells: list[str],
+        colwidths: list[int],
+        colaligns: list[str],
+        table_type: str,
+    ) -> str:
         """Format rows of a table to fit terminal.
 
         :param list(str) padded_cells: row where each cell is padded with
@@ -165,6 +180,9 @@ def _interrogate_line_formatter(
         :param list(int) colwidths: list of widths, by column order.
         :param list(str) colaligns: list of column alignment, by column
             order. Possible values: ``"left"`` or ``"right"``
+        :param str table_type: Table type of either "detailed" (second
+            level of output verbosity), or "summary" (first level of
+            output verbosity).
 
         :return: a formatted table row
         :rtype: str
@@ -223,7 +241,7 @@ def _interrogate_line_formatter(
         ret = sep + sep.join(to_join) + sep
         return ret.rstrip()
 
-    def get_table_formatter(self, table_type):
+    def get_table_formatter(self, table_type: str) -> tabulate.TableFormat:
         """Get a `tabulate` table formatter.
 
         :param str table_type: Table type of either "detailed" (second
diff --git a/src/interrogate/visit.py b/src/interrogate/visit.py
index 1748bf0..e9aa906 100644
--- a/src/interrogate/visit.py
+++ b/src/interrogate/visit.py
@@ -1,11 +1,21 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """AST traversal for finding docstrings."""
+from __future__ import annotations
 
 import ast
 import os
 
+from typing import Union
+
 import attr
 
+from interrogate.config import InterrogateConfig
+
+
+DocumentableFunc = Union[ast.AsyncFunctionDef, ast.FunctionDef]
+DocumentableFuncOrClass = Union[DocumentableFunc, ast.ClassDef]
+DocumentableNode = Union[DocumentableFuncOrClass, ast.Module]
+
 
 @attr.s(eq=False)
 class CovNode:
@@ -26,15 +36,15 @@ class CovNode:
     :param CovNode _parent: parent node of current CovNode, if any.
     """
 
-    name = attr.ib()
-    path = attr.ib()
-    level = attr.ib()
-    lineno = attr.ib()
-    covered = attr.ib()
-    node_type = attr.ib()
-    is_nested_func = attr.ib()
-    is_nested_cls = attr.ib()
-    parent = attr.ib()
+    name: str = attr.ib()
+    path: str = attr.ib()
+    level: int = attr.ib()
+    lineno: int | None = attr.ib()
+    covered: bool = attr.ib()
+    node_type: str = attr.ib()
+    is_nested_func: bool = attr.ib()
+    is_nested_cls: bool = attr.ib()
+    parent: CovNode | None = attr.ib()
 
 
 class CoverageVisitor(ast.NodeVisitor):
@@ -44,21 +54,21 @@ class CoverageVisitor(ast.NodeVisitor):
     :param config.InterrogateConfig config: configuration.
     """
 
-    def __init__(self, filename, config):
+    def __init__(self, filename: str, config: InterrogateConfig):
         self.filename = filename
-        self.stack = []
-        self.nodes = []
         self.config = config
+        self.stack: list[CovNode] = []
+        self.nodes: list[CovNode] = []
 
     @staticmethod
-    def _has_doc(node):
+    def _has_doc(node: DocumentableNode) -> bool:
         """Return if node has docstrings."""
         return (
             ast.get_docstring(node) is not None
-            and ast.get_docstring(node).strip() != ""
+            and ast.get_docstring(node).strip() != ""  # type: ignore
         )
 
-    def _visit_helper(self, node):
+    def _visit_helper(self, node: DocumentableNode) -> None:
         """Recursively visit AST node for docstrings."""
         if not hasattr(node, "name"):
             node_name = os.path.basename(self.filename)
@@ -99,7 +109,7 @@ def _visit_helper(self, node):
 
         self.stack.pop()
 
-    def _is_nested_func(self, parent, node_type):
+    def _is_nested_func(self, parent: CovNode | None, node_type: str) -> bool:
         """Is node a nested func/method of another func/method."""
         if parent is None:
             return False
@@ -108,7 +118,7 @@ def _is_nested_func(self, parent, node_type):
             return True
         return False
 
-    def _is_nested_cls(self, parent, node_type):
+    def _is_nested_cls(self, parent: CovNode | None, node_type: str) -> bool:
         """Is node a nested func/method of another func/method."""
         if parent is None:
             return False
@@ -120,7 +130,7 @@ def _is_nested_cls(self, parent, node_type):
             return True
         return False
 
-    def _is_private(self, node):
+    def _is_private(self, node: DocumentableFuncOrClass) -> bool:
         """Is node private (i.e. __MyClass, __my_func)."""
         if node.name.endswith("__"):
             return False
@@ -128,7 +138,7 @@ def _is_private(self, node):
             return False
         return True
 
-    def _is_semiprivate(self, node):
+    def _is_semiprivate(self, node: DocumentableFuncOrClass) -> bool:
         """Is node semiprivate (i.e. _MyClass, _my_func)."""
         if node.name.endswith("__"):
             return False
@@ -138,7 +148,7 @@ def _is_semiprivate(self, node):
             return False
         return True
 
-    def _is_ignored_common(self, node):
+    def _is_ignored_common(self, node: DocumentableFuncOrClass) -> bool:
         """Commonly-shared ignore checkers."""
         is_private = self._is_private(node)
         is_semiprivate = self._is_semiprivate(node)
@@ -155,7 +165,7 @@ def _is_ignored_common(self, node):
                     return True
         return False
 
-    def _has_property_decorators(self, node):
+    def _has_property_decorators(self, node: DocumentableFuncOrClass) -> bool:
         """Detect if node has property get/setter/deleter decorators."""
         if not hasattr(node, "decorator_list"):
             return False
@@ -171,7 +181,7 @@ def _has_property_decorators(self, node):
                     return True
         return False
 
-    def _has_setters(self, node):
+    def _has_setters(self, node: DocumentableFuncOrClass) -> bool:
         """Detect if node has property get/setter decorators."""
         if not hasattr(node, "decorator_list"):
             return False
@@ -182,7 +192,7 @@ def _has_setters(self, node):
                     return True
         return False
 
-    def _has_overload_decorator(self, node):
+    def _has_overload_decorator(self, node: DocumentableFuncOrClass) -> bool:
         """Detect if node has a typing.overload decorator."""
         if not hasattr(node, "decorator_list"):
             return False
@@ -202,7 +212,7 @@ def _has_overload_decorator(self, node):
                 return True
         return False
 
-    def _is_func_ignored(self, node):
+    def _is_func_ignored(self, node: DocumentableFuncOrClass) -> bool:
         """Should the AST visitor ignore this func/method node."""
         is_init = node.name == "__init__"
         is_magic = all(
@@ -229,18 +239,18 @@ def _is_func_ignored(self, node):
 
         return self._is_ignored_common(node)
 
-    def _is_class_ignored(self, node):
+    def _is_class_ignored(self, node: DocumentableFuncOrClass) -> bool:
         """Should the AST visitor ignore this class node."""
         return self._is_ignored_common(node)
 
-    def visit_Module(self, node):
+    def visit_Module(self, node: DocumentableNode) -> None:
         """Visit module for docstrings.
 
         :param ast.Module node: a module AST node.
         """
         self._visit_helper(node)
 
-    def visit_ClassDef(self, node):
+    def visit_ClassDef(self, node: DocumentableFuncOrClass) -> None:
         """Visit class for docstrings.
 
         :param ast.ClassDef node: a class AST node.
@@ -249,7 +259,7 @@ def visit_ClassDef(self, node):
             return
         self._visit_helper(node)
 
-    def visit_FunctionDef(self, node):
+    def visit_FunctionDef(self, node: DocumentableFuncOrClass) -> None:
         """Visit function or method for docstrings.
 
         :param ast.FunctionDef node: a function/method AST node.
@@ -258,7 +268,7 @@ def visit_FunctionDef(self, node):
             return
         self._visit_helper(node)
 
-    def visit_AsyncFunctionDef(self, node):
+    def visit_AsyncFunctionDef(self, node: DocumentableFuncOrClass) -> None:
         """Visit async function or method for docstrings.
 
         :param ast.AsyncFunctionDef node: a async function/method AST node.
diff --git a/tests/functional/__init__.py b/tests/functional/__init__.py
index 42627c2..559df4a 100644
--- a/tests/functional/__init__.py
+++ b/tests/functional/__init__.py
@@ -1,2 +1,2 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Yay functional tests for the ``interrogate`` package!"""
diff --git a/tests/functional/sample/__init__.py b/tests/functional/sample/__init__.py
index 3c0a94d..8cee339 100644
--- a/tests/functional/sample/__init__.py
+++ b/tests/functional/sample/__init__.py
@@ -1,2 +1,2 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Some init module docs"""
diff --git a/tests/functional/sample/child_sample/__init__.py b/tests/functional/sample/child_sample/__init__.py
index 55f709e..5a052c9 100644
--- a/tests/functional/sample/child_sample/__init__.py
+++ b/tests/functional/sample/child_sample/__init__.py
@@ -1,2 +1,2 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 # intentionally no docstrings here
diff --git a/tests/functional/sample/child_sample/child_sample_module.py b/tests/functional/sample/child_sample/child_sample_module.py
index 3d6c4e6..872073d 100644
--- a/tests/functional/sample/child_sample/child_sample_module.py
+++ b/tests/functional/sample/child_sample/child_sample_module.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 # intentionally no docstrings here
 
 
diff --git a/tests/functional/sample/full.py b/tests/functional/sample/full.py
index 9c97f90..bfc3b01 100644
--- a/tests/functional/sample/full.py
+++ b/tests/functional/sample/full.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Sample module-level docs"""
 import typing
 
diff --git a/tests/functional/sample/partial.py b/tests/functional/sample/partial.py
index 663645c..96eb6e4 100644
--- a/tests/functional/sample/partial.py
+++ b/tests/functional/sample/partial.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Sample module-level docs"""
 import typing
 
diff --git a/tests/functional/test_cli.py b/tests/functional/test_cli.py
index f4ae5b3..b03a555 100644
--- a/tests/functional/test_cli.py
+++ b/tests/functional/test_cli.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Functional tests for the CLI and implicitly interrogate/visit.py."""
 
 import os
@@ -8,8 +8,7 @@
 
 from click import testing
 
-from interrogate import cli
-from interrogate import config
+from interrogate import cli, config
 
 
 HERE = os.path.abspath(os.path.join(os.path.abspath(__file__), os.path.pardir))
diff --git a/tests/functional/test_coverage.py b/tests/functional/test_coverage.py
index 47906d0..4401828 100644
--- a/tests/functional/test_coverage.py
+++ b/tests/functional/test_coverage.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Functional tests for interrogate/coverage.py."""
 
 import os
@@ -6,8 +6,7 @@
 
 import pytest
 
-from interrogate import config
-from interrogate import coverage
+from interrogate import config, coverage
 
 
 HERE = os.path.abspath(os.path.join(os.path.abspath(__file__), os.path.pardir))
diff --git a/tests/unit/__init__.py b/tests/unit/__init__.py
index 377a005..ca2174a 100644
--- a/tests/unit/__init__.py
+++ b/tests/unit/__init__.py
@@ -1,2 +1,2 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Yay unit tests for the ``interrogate`` package!"""
diff --git a/tests/unit/test_badge_gen.py b/tests/unit/test_badge_gen.py
index 8cf58f3..4ecca83 100644
--- a/tests/unit/test_badge_gen.py
+++ b/tests/unit/test_badge_gen.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Unit tests for interrogate/badge_gen.py module"""
 
 import os
diff --git a/tests/unit/test_config.py b/tests/unit/test_config.py
index 5421a13..df574e8 100644
--- a/tests/unit/test_config.py
+++ b/tests/unit/test_config.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Unit tests for interrogate/config.py module"""
 
 import configparser
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index 64f9c79..68c897b 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Lynn Root
+# Copyright 2020-2024 Lynn Root
 """Unit tests for interrogate/utils.py module"""
 
 import re
@@ -6,8 +6,7 @@
 
 import pytest
 
-from interrogate import config
-from interrogate import utils
+from interrogate import config, utils
 
 
 IS_WINDOWS = sys.platform in ("cygwin", "win32")
diff --git a/tox.ini b/tox.ini
index 313a7fc..eba49e3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,6 +5,7 @@ env_list =
     docs,
     lint,
     manifest,
+    mypy,
     coverage-report
 
 [testenv]
@@ -18,6 +19,10 @@ extras =
     png: png
 commands = coverage run -m pytest {posargs}
 
+[testenv:mypy]
+extras =
+    mypy: typing
+commands = mypy src/
 
 [testenv:lint]
 base_python = python3.10