diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index dca2fb10..7d43bcbd 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -58,8 +58,7 @@ repos:
     hooks:
       - id: mypy
         name: Check Python types
-        additional_dependencies: [openslide-bin, pillow, types-setuptools]
-        exclude: "^(doc/.*|tests/.*|examples/deepzoom/.*)$"
+        additional_dependencies: [flask, openslide-bin, pillow, types-setuptools]
 
   - repo: https://github.com/rstcheck/rstcheck
     rev: v6.2.4
diff --git a/doc/conf.py b/doc/conf.py
index 4cdc306d..79718126 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -174,98 +174,6 @@
 # This is the file name suffix for HTML files (e.g. ".xhtml").
 # html_file_suffix = None
 
-# Output file base name for HTML help builder.
-htmlhelp_basename = 'OpenSlidePythondoc'
-
-
-# -- Options for LaTeX output --------------------------------------------------
-
-latex_elements = {
-    # The paper size ('letterpaper' or 'a4paper').
-    # 'papersize': 'letterpaper',
-    # The font size ('10pt', '11pt' or '12pt').
-    # 'pointsize': '10pt',
-    # Additional stuff for the LaTeX preamble.
-    # 'preamble': '',
-}
-
-# Grouping the document tree into LaTeX files. List of tuples
-# (source start file, target name, title, author, documentclass [howto/manual]).
-latex_documents = [
-    (
-        'index',
-        'OpenSlidePython.tex',
-        'OpenSlide Python Documentation',
-        'OpenSlide project',
-        'manual',
-    ),
-]
-
-# The name of an image file (relative to this directory) to place at the top of
-# the title page.
-# latex_logo = None
-
-# For "manual" documents, if this is true, then toplevel headings are parts,
-# not chapters.
-# latex_use_parts = False
-
-# If true, show page references after internal links.
-# latex_show_pagerefs = False
-
-# If true, show URL addresses after external links.
-# latex_show_urls = False
-
-# Documents to append as an appendix to all manuals.
-# latex_appendices = []
-
-# If false, no module index is generated.
-# latex_domain_indices = True
-
-
-# -- Options for manual page output --------------------------------------------
-
-# One entry per manual page. List of tuples
-# (source start file, name, description, authors, manual section).
-man_pages = [
-    (
-        'index',
-        'openslidepython',
-        'OpenSlide Python Documentation',
-        ['OpenSlide project'],
-        1,
-    )
-]
-
-# If true, show URL addresses after external links.
-# man_show_urls = False
-
-
-# -- Options for Texinfo output ------------------------------------------------
-
-# Grouping the document tree into Texinfo files. List of tuples
-# (source start file, target name, title, author,
-#  dir menu entry, description, category)
-texinfo_documents = [
-    (
-        'index',
-        'OpenSlidePython',
-        'OpenSlide Python Documentation',
-        'OpenSlide project',
-        'OpenSlidePython',
-        'One line description of project.',
-        'Miscellaneous',
-    ),
-]
-
-# Documents to append as an appendix to all manuals.
-# texinfo_appendices = []
-
-# If false, no module index is generated.
-# texinfo_domain_indices = True
-
-# How to display URL addresses: 'footnote', 'no', or 'inline'.
-# texinfo_show_urls = 'footnote'
-
 
 # intersphinx
 intersphinx_mapping = {
diff --git a/doc/jekyll_fix.py b/doc/jekyll_fix.py
index b479e00e..798b8897 100644
--- a/doc/jekyll_fix.py
+++ b/doc/jekyll_fix.py
@@ -27,6 +27,7 @@
 
 import os
 
+from sphinx.application import Sphinx
 from sphinx.util import logging
 from sphinx.util.console import bold
 
@@ -41,7 +42,7 @@
 REWRITE_EXTENSIONS = {'.html', '.js'}
 
 
-def remove_path_underscores(app, exception):
+def remove_path_underscores(app: Sphinx, exception: Exception | None) -> None:
     if exception:
         return
     # Get logger
@@ -82,5 +83,5 @@ def remove_path_underscores(app, exception):
     logger.info('done')
 
 
-def setup(app):
+def setup(app: Sphinx) -> None:
     app.connect('build-finished', remove_path_underscores)
diff --git a/examples/deepzoom/deepzoom_multiserver.py b/examples/deepzoom/deepzoom_multiserver.py
index de0c2061..82b4734a 100755
--- a/examples/deepzoom/deepzoom_multiserver.py
+++ b/examples/deepzoom/deepzoom_multiserver.py
@@ -24,18 +24,24 @@
 from argparse import ArgumentParser
 import base64
 from collections import OrderedDict
+from collections.abc import Callable
 from io import BytesIO
 import os
 from threading import Lock
+from typing import TYPE_CHECKING, Any, Literal
 import zlib
 
-from PIL import ImageCms
-from flask import Flask, abort, make_response, render_template, url_for
+from PIL import Image, ImageCms
+from flask import Flask, Response, abort, make_response, render_template, url_for
+
+if TYPE_CHECKING:
+    # Python 3.10+
+    from typing import TypeAlias
 
 if os.name == 'nt':
     _dll_path = os.getenv('OPENSLIDE_PATH')
     if _dll_path is not None:
-        with os.add_dll_directory(_dll_path):
+        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined]
             import openslide
     else:
         import openslide
@@ -62,10 +68,36 @@
 )
 SRGB_PROFILE = ImageCms.getOpenProfile(BytesIO(SRGB_PROFILE_BYTES))
 
+if TYPE_CHECKING:
+    ColorMode: TypeAlias = Literal[
+        'default',
+        'absolute-colorimetric',
+        'perceptual',
+        'relative-colorimetric',
+        'saturation',
+        'embed',
+        'ignore',
+    ]
+    Transform: TypeAlias = Callable[[Image.Image], None]
+
+
+class DeepZoomMultiServer(Flask):
+    basedir: str
+    cache: _SlideCache
+
+
+class AnnotatedDeepZoomGenerator(DeepZoomGenerator):
+    filename: str
+    mpp: float
+    transform: Transform
+
 
-def create_app(config=None, config_file=None):
+def create_app(
+    config: dict[str, Any] | None = None,
+    config_file: str | None = None,
+) -> Flask:
     # Create and configure app
-    app = Flask(__name__)
+    app = DeepZoomMultiServer(__name__)
     app.config.from_mapping(
         SLIDE_DIR='.',
         SLIDE_CACHE_SIZE=10,
@@ -99,7 +131,7 @@ def create_app(config=None, config_file=None):
     )
 
     # Helper functions
-    def get_slide(path):
+    def get_slide(path: str) -> AnnotatedDeepZoomGenerator:
         path = os.path.abspath(os.path.join(app.basedir, path))
         if not path.startswith(app.basedir + os.path.sep):
             # Directory traversal
@@ -115,11 +147,11 @@ def get_slide(path):
 
     # Set up routes
     @app.route('/')
-    def index():
+    def index() -> str:
         return render_template('files.html', root_dir=_Directory(app.basedir))
 
     @app.route('/<path:path>')
-    def slide(path):
+    def slide(path: str) -> str:
         slide = get_slide(path)
         slide_url = url_for('dzi', path=path)
         return render_template(
@@ -130,7 +162,7 @@ def slide(path):
         )
 
     @app.route('/<path:path>.dzi')
-    def dzi(path):
+    def dzi(path: str) -> Response:
         slide = get_slide(path)
         format = app.config['DEEPZOOM_FORMAT']
         resp = make_response(slide.get_dzi(format))
@@ -138,7 +170,7 @@ def dzi(path):
         return resp
 
     @app.route('/<path:path>_files/<int:level>/<int:col>_<int:row>.<format>')
-    def tile(path, level, col, row, format):
+    def tile(path: str, level: int, col: int, row: int, format: str) -> Response:
         slide = get_slide(path)
         format = format.lower()
         if format != 'jpeg' and format != 'png':
@@ -165,19 +197,27 @@ def tile(path, level, col, row, format):
 
 
 class _SlideCache:
-    def __init__(self, cache_size, tile_cache_mb, dz_opts, color_mode):
+    def __init__(
+        self,
+        cache_size: int,
+        tile_cache_mb: int,
+        dz_opts: dict[str, Any],
+        color_mode: ColorMode,
+    ):
         self.cache_size = cache_size
         self.dz_opts = dz_opts
         self.color_mode = color_mode
         self._lock = Lock()
-        self._cache = OrderedDict()
+        self._cache: OrderedDict[str, AnnotatedDeepZoomGenerator] = OrderedDict()
         # Share a single tile cache among all slide handles, if supported
         try:
-            self._tile_cache = OpenSlideCache(tile_cache_mb * 1024 * 1024)
+            self._tile_cache: OpenSlideCache | None = OpenSlideCache(
+                tile_cache_mb * 1024 * 1024
+            )
         except OpenSlideVersionError:
             self._tile_cache = None
 
-    def get(self, path):
+    def get(self, path: str) -> AnnotatedDeepZoomGenerator:
         with self._lock:
             if path in self._cache:
                 # Move to end of LRU
@@ -188,7 +228,7 @@ def get(self, path):
         osr = OpenSlide(path)
         if self._tile_cache is not None:
             osr.set_cache(self._tile_cache)
-        slide = DeepZoomGenerator(osr, **self.dz_opts)
+        slide = AnnotatedDeepZoomGenerator(osr, **self.dz_opts)
         try:
             mpp_x = osr.properties[openslide.PROPERTY_NAME_MPP_X]
             mpp_y = osr.properties[openslide.PROPERTY_NAME_MPP_Y]
@@ -204,7 +244,7 @@ def get(self, path):
                 self._cache[path] = slide
         return slide
 
-    def _get_transform(self, image):
+    def _get_transform(self, image: OpenSlide) -> Transform:
         if image.color_profile is None:
             return lambda img: None
         mode = self.color_mode
@@ -215,7 +255,7 @@ def _get_transform(self, image):
             # embed ICC profile in tiles
             return lambda img: None
         elif mode == 'default':
-            intent = ImageCms.getDefaultIntent(image.color_profile)
+            intent = ImageCms.Intent(ImageCms.getDefaultIntent(image.color_profile))
         elif mode == 'absolute-colorimetric':
             intent = ImageCms.Intent.ABSOLUTE_COLORIMETRIC
         elif mode == 'relative-colorimetric':
@@ -232,10 +272,10 @@ def _get_transform(self, image):
             'RGB',
             'RGB',
             intent,
-            0,
+            ImageCms.Flags(0),
         )
 
-        def xfrm(img):
+        def xfrm(img: Image.Image) -> None:
             ImageCms.applyTransform(img, transform, True)
             # Some browsers assume we intend the display's color space if we
             # don't embed the profile.  Pillow's serialization is larger, so
@@ -246,9 +286,9 @@ def xfrm(img):
 
 
 class _Directory:
-    def __init__(self, basedir, relpath=''):
+    def __init__(self, basedir: str, relpath: str = ''):
         self.name = os.path.basename(relpath)
-        self.children = []
+        self.children: list[_Directory | _SlideFile] = []
         for name in sorted(os.listdir(os.path.join(basedir, relpath))):
             cur_relpath = os.path.join(relpath, name)
             cur_path = os.path.join(basedir, cur_relpath)
@@ -261,7 +301,7 @@ def __init__(self, basedir, relpath=''):
 
 
 class _SlideFile:
-    def __init__(self, relpath):
+    def __init__(self, relpath: str):
         self.name = os.path.basename(relpath)
         self.url_path = relpath
 
diff --git a/examples/deepzoom/deepzoom_server.py b/examples/deepzoom/deepzoom_server.py
index 0b82aeda..1512460f 100755
--- a/examples/deepzoom/deepzoom_server.py
+++ b/examples/deepzoom/deepzoom_server.py
@@ -23,26 +23,32 @@
 
 from argparse import ArgumentParser
 import base64
+from collections.abc import Callable
 from io import BytesIO
 import os
 import re
+from typing import TYPE_CHECKING, Any, Literal, Mapping
 from unicodedata import normalize
 import zlib
 
-from PIL import ImageCms
-from flask import Flask, abort, make_response, render_template, url_for
+from PIL import Image, ImageCms
+from flask import Flask, Response, abort, make_response, render_template, url_for
+
+if TYPE_CHECKING:
+    # Python 3.10+
+    from typing import TypeAlias
 
 if os.name == 'nt':
     _dll_path = os.getenv('OPENSLIDE_PATH')
     if _dll_path is not None:
-        with os.add_dll_directory(_dll_path):
+        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined]
             import openslide
     else:
         import openslide
 else:
     import openslide
 
-from openslide import ImageSlide, open_slide
+from openslide import AbstractSlide, ImageSlide, open_slide
 from openslide.deepzoom import DeepZoomGenerator
 
 SLIDE_NAME = 'slide'
@@ -64,10 +70,33 @@
 )
 SRGB_PROFILE = ImageCms.getOpenProfile(BytesIO(SRGB_PROFILE_BYTES))
 
+if TYPE_CHECKING:
+    ColorMode: TypeAlias = Literal[
+        'default',
+        'absolute-colorimetric',
+        'perceptual',
+        'relative-colorimetric',
+        'saturation',
+        'embed',
+        'ignore',
+    ]
+    Transform: TypeAlias = Callable[[Image.Image], None]
+
+
+class DeepZoomServer(Flask):
+    slides: dict[str, DeepZoomGenerator]
+    transforms: dict[str, Transform]
+    slide_properties: Mapping[str, str]
+    associated_images: list[str]
+    slide_mpp: float
+
 
-def create_app(config=None, config_file=None):
+def create_app(
+    config: dict[str, Any] | None = None,
+    config_file: str | None = None,
+) -> Flask:
     # Create and configure app
-    app = Flask(__name__)
+    app = DeepZoomServer(__name__)
     app.config.from_mapping(
         DEEPZOOM_SLIDE=None,
         DEEPZOOM_FORMAT='jpeg',
@@ -117,7 +146,7 @@ def create_app(config=None, config_file=None):
 
     # Set up routes
     @app.route('/')
-    def index():
+    def index() -> str:
         slide_url = url_for('dzi', slug=SLIDE_NAME)
         associated_urls = {
             name: url_for('dzi', slug=slugify(name)) for name in app.associated_images
@@ -131,7 +160,7 @@ def index():
         )
 
     @app.route('/<slug>.dzi')
-    def dzi(slug):
+    def dzi(slug: str) -> Response:
         format = app.config['DEEPZOOM_FORMAT']
         try:
             resp = make_response(app.slides[slug].get_dzi(format))
@@ -142,7 +171,7 @@ def dzi(slug):
             abort(404)
 
     @app.route('/<slug>_files/<int:level>/<int:col>_<int:row>.<format>')
-    def tile(slug, level, col, row, format):
+    def tile(slug: str, level: int, col: int, row: int, format: str) -> Response:
         format = format.lower()
         if format != 'jpeg' and format != 'png':
             # Not supported by Deep Zoom
@@ -170,12 +199,12 @@ def tile(slug, level, col, row, format):
     return app
 
 
-def slugify(text):
+def slugify(text: str) -> str:
     text = normalize('NFKD', text.lower()).encode('ascii', 'ignore').decode()
     return re.sub('[^a-z0-9]+', '-', text)
 
 
-def get_transform(image, mode):
+def get_transform(image: AbstractSlide, mode: ColorMode) -> Transform:
     if image.color_profile is None:
         return lambda img: None
     if mode == 'ignore':
@@ -185,7 +214,7 @@ def get_transform(image, mode):
         # embed ICC profile in tiles
         return lambda img: None
     elif mode == 'default':
-        intent = ImageCms.getDefaultIntent(image.color_profile)
+        intent = ImageCms.Intent(ImageCms.getDefaultIntent(image.color_profile))
     elif mode == 'absolute-colorimetric':
         intent = ImageCms.Intent.ABSOLUTE_COLORIMETRIC
     elif mode == 'relative-colorimetric':
@@ -202,10 +231,10 @@ def get_transform(image, mode):
         'RGB',
         'RGB',
         intent,
-        0,
+        ImageCms.Flags(0),
     )
 
-    def xfrm(img):
+    def xfrm(img: Image.Image) -> None:
         ImageCms.applyTransform(img, transform, True)
         # Some browsers assume we intend the display's color space if we don't
         # embed the profile.  Pillow's serialization is larger, so use ours.
diff --git a/examples/deepzoom/deepzoom_tile.py b/examples/deepzoom/deepzoom_tile.py
index aad834d9..211b9111 100755
--- a/examples/deepzoom/deepzoom_tile.py
+++ b/examples/deepzoom/deepzoom_tile.py
@@ -25,29 +25,36 @@
 
 from argparse import ArgumentParser
 import base64
+from collections.abc import Callable
 from io import BytesIO
 import json
 from multiprocessing import JoinableQueue, Process
+import multiprocessing.queues
 import os
 import re
 import shutil
 import sys
+from typing import TYPE_CHECKING, Literal
 from unicodedata import normalize
 import zlib
 
-from PIL import ImageCms
+from PIL import Image, ImageCms
+
+if TYPE_CHECKING:
+    # Python 3.10+
+    from typing import TypeAlias
 
 if os.name == 'nt':
     _dll_path = os.getenv('OPENSLIDE_PATH')
     if _dll_path is not None:
-        with os.add_dll_directory(_dll_path):
+        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined]
             import openslide
     else:
         import openslide
 else:
     import openslide
 
-from openslide import ImageSlide, open_slide
+from openslide import AbstractSlide, ImageSlide, open_slide
 from openslide.deepzoom import DeepZoomGenerator
 
 VIEWER_SLIDE_NAME = 'slide'
@@ -69,12 +76,34 @@
 )
 SRGB_PROFILE = ImageCms.getOpenProfile(BytesIO(SRGB_PROFILE_BYTES))
 
+if TYPE_CHECKING:
+    ColorMode: TypeAlias = Literal[
+        'default',
+        'absolute-colorimetric',
+        'perceptual',
+        'relative-colorimetric',
+        'saturation',
+        'embed',
+        'ignore',
+    ]
+    TileQueue: TypeAlias = multiprocessing.queues.JoinableQueue[
+        tuple[str | None, int, tuple[int, int], str] | None
+    ]
+    Transform: TypeAlias = Callable[[Image.Image], None]
+
 
 class TileWorker(Process):
     """A child process that generates and writes tiles."""
 
     def __init__(
-        self, queue, slidepath, tile_size, overlap, limit_bounds, quality, color_mode
+        self,
+        queue: TileQueue,
+        slidepath: str,
+        tile_size: int,
+        overlap: int,
+        limit_bounds: bool,
+        quality: int,
+        color_mode: ColorMode,
     ):
         Process.__init__(self, name='TileWorker')
         self.daemon = True
@@ -85,9 +114,9 @@ def __init__(
         self._limit_bounds = limit_bounds
         self._quality = quality
         self._color_mode = color_mode
-        self._slide = None
+        self._slide: AbstractSlide | None = None
 
-    def run(self):
+    def run(self) -> None:
         self._slide = open_slide(self._slidepath)
         last_associated = None
         dz, transform = self._get_dz_and_transform()
@@ -107,9 +136,12 @@ def run(self):
             )
             self._queue.task_done()
 
-    def _get_dz_and_transform(self, associated=None):
+    def _get_dz_and_transform(
+        self, associated: str | None = None
+    ) -> tuple[DeepZoomGenerator, Transform]:
+        assert self._slide is not None
         if associated is not None:
-            image = ImageSlide(self._slide.associated_images[associated])
+            image: AbstractSlide = ImageSlide(self._slide.associated_images[associated])
         else:
             image = self._slide
         dz = DeepZoomGenerator(
@@ -117,7 +149,7 @@ def _get_dz_and_transform(self, associated=None):
         )
         return dz, self._get_transform(image)
 
-    def _get_transform(self, image):
+    def _get_transform(self, image: AbstractSlide) -> Transform:
         if image.color_profile is None:
             return lambda img: None
         mode = self._color_mode
@@ -128,7 +160,7 @@ def _get_transform(self, image):
             # embed ICC profile in tiles
             return lambda img: None
         elif mode == 'default':
-            intent = ImageCms.getDefaultIntent(image.color_profile)
+            intent = ImageCms.Intent(ImageCms.getDefaultIntent(image.color_profile))
         elif mode == 'absolute-colorimetric':
             intent = ImageCms.Intent.ABSOLUTE_COLORIMETRIC
         elif mode == 'relative-colorimetric':
@@ -145,10 +177,10 @@ def _get_transform(self, image):
             'RGB',
             'RGB',
             intent,
-            0,
+            ImageCms.Flags(0),
         )
 
-        def xfrm(img):
+        def xfrm(img: Image.Image) -> None:
             ImageCms.applyTransform(img, transform, True)
             # Some browsers assume we intend the display's color space if we
             # don't embed the profile.  Pillow's serialization is larger, so
@@ -161,7 +193,14 @@ def xfrm(img):
 class DeepZoomImageTiler:
     """Handles generation of tiles and metadata for a single image."""
 
-    def __init__(self, dz, basename, format, associated, queue):
+    def __init__(
+        self,
+        dz: DeepZoomGenerator,
+        basename: str,
+        format: str,
+        associated: str | None,
+        queue: TileQueue,
+    ):
         self._dz = dz
         self._basename = basename
         self._format = format
@@ -169,11 +208,11 @@ def __init__(self, dz, basename, format, associated, queue):
         self._queue = queue
         self._processed = 0
 
-    def run(self):
+    def run(self) -> None:
         self._write_tiles()
         self._write_dzi()
 
-    def _write_tiles(self):
+    def _write_tiles(self) -> None:
         for level in range(self._dz.level_count):
             tiledir = os.path.join("%s_files" % self._basename, str(level))
             if not os.path.exists(tiledir):
@@ -188,7 +227,7 @@ def _write_tiles(self):
                         self._queue.put((self._associated, level, (col, row), tilename))
                     self._tile_done()
 
-    def _tile_done(self):
+    def _tile_done(self) -> None:
         self._processed += 1
         count, total = self._processed, self._dz.tile_count
         if count % 100 == 0 or count == total:
@@ -201,11 +240,11 @@ def _tile_done(self):
             if count == total:
                 print(file=sys.stderr)
 
-    def _write_dzi(self):
+    def _write_dzi(self) -> None:
         with open('%s.dzi' % self._basename, 'w') as fh:
             fh.write(self.get_dzi())
 
-    def get_dzi(self):
+    def get_dzi(self) -> str:
         return self._dz.get_dzi(self._format)
 
 
@@ -214,16 +253,16 @@ class DeepZoomStaticTiler:
 
     def __init__(
         self,
-        slidepath,
-        basename,
-        format,
-        tile_size,
-        overlap,
-        limit_bounds,
-        quality,
-        color_mode,
-        workers,
-        with_viewer,
+        slidepath: str,
+        basename: str,
+        format: str,
+        tile_size: int,
+        overlap: int,
+        limit_bounds: bool,
+        quality: int,
+        color_mode: ColorMode,
+        workers: int,
+        with_viewer: bool,
     ):
         if with_viewer:
             # Check extra dependency before doing a bunch of work
@@ -234,11 +273,11 @@ def __init__(
         self._tile_size = tile_size
         self._overlap = overlap
         self._limit_bounds = limit_bounds
-        self._queue = JoinableQueue(2 * workers)
+        self._queue: TileQueue = JoinableQueue(2 * workers)
         self._workers = workers
         self._color_mode = color_mode
         self._with_viewer = with_viewer
-        self._dzi_data = {}
+        self._dzi_data: dict[str, str] = {}
         for _i in range(workers):
             TileWorker(
                 self._queue,
@@ -250,7 +289,7 @@ def __init__(
                 color_mode,
             ).start()
 
-    def run(self):
+    def run(self) -> None:
         self._run_image()
         if self._with_viewer:
             for name in self._slide.associated_images:
@@ -259,7 +298,7 @@ def run(self):
             self._write_static()
         self._shutdown()
 
-    def _run_image(self, associated=None):
+    def _run_image(self, associated: str | None = None) -> None:
         """Run a single image from self._slide."""
         if associated is None:
             image = self._slide
@@ -277,14 +316,14 @@ def _run_image(self, associated=None):
         tiler.run()
         self._dzi_data[self._url_for(associated)] = tiler.get_dzi()
 
-    def _url_for(self, associated):
+    def _url_for(self, associated: str | None) -> str:
         if associated is None:
             base = VIEWER_SLIDE_NAME
         else:
             base = self._slugify(associated)
         return '%s.dzi' % base
 
-    def _write_html(self):
+    def _write_html(self) -> None:
         import jinja2
 
         # https://docs.python.org/3/reference/import.html#main-spec
@@ -321,13 +360,13 @@ def _write_html(self):
         with open(os.path.join(self._basename, 'index.html'), 'w') as fh:
             fh.write(data)
 
-    def _write_static(self):
+    def _write_static(self) -> None:
         basesrc = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'static')
         basedst = os.path.join(self._basename, 'static')
         self._copydir(basesrc, basedst)
         self._copydir(os.path.join(basesrc, 'images'), os.path.join(basedst, 'images'))
 
-    def _copydir(self, src, dest):
+    def _copydir(self, src: str, dest: str) -> None:
         if not os.path.exists(dest):
             os.makedirs(dest)
         for name in os.listdir(src):
@@ -336,11 +375,11 @@ def _copydir(self, src, dest):
                 shutil.copy(srcpath, os.path.join(dest, name))
 
     @classmethod
-    def _slugify(cls, text):
+    def _slugify(cls, text: str) -> str:
         text = normalize('NFKD', text.lower()).encode('ascii', 'ignore').decode()
         return re.sub('[^a-z0-9]+', '_', text)
 
-    def _shutdown(self):
+    def _shutdown(self) -> None:
         for _i in range(self._workers):
             self._queue.put(None)
         self._queue.join()
diff --git a/openslide/py.typed b/openslide/py.typed
new file mode 100644
index 00000000..e69de29b
diff --git a/pyproject.toml b/pyproject.toml
index 8fd7be02..42ee741b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -24,6 +24,7 @@ classifiers = [
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Topic :: Scientific/Engineering :: Bio-Informatics",
+    "Typing :: Typed",
 ]
 requires-python = ">= 3.8"
 dependencies = ["Pillow"]
diff --git a/setup.py b/setup.py
index a4702e72..4a5e532c 100644
--- a/setup.py
+++ b/setup.py
@@ -21,4 +21,7 @@
         # tag wheel for Limited API
         'bdist_wheel': {'py_limited_api': 'cp311'} if _abi3 else {},
     },
+    package_data={
+        'openslide': ['py.typed'],
+    },
 )
diff --git a/tests/common.py b/tests/common.py
index 9efd1c26..28bc8bfb 100644
--- a/tests/common.py
+++ b/tests/common.py
@@ -30,9 +30,9 @@
     # environment.
     _dll_path = os.getenv('OPENSLIDE_PATH')
     if _dll_path is not None:
-        with os.add_dll_directory(_dll_path):
+        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined]
             import openslide  # noqa: F401  module-imported-but-unused
 
 
-def file_path(name):
+def file_path(name: str) -> Path:
     return Path(__file__).parent / 'fixtures' / name
diff --git a/tests/test_base.py b/tests/test_base.py
index d03ce7cf..2ed9116e 100644
--- a/tests/test_base.py
+++ b/tests/test_base.py
@@ -28,13 +28,13 @@
 
 
 class TestLibrary(unittest.TestCase):
-    def test_open_slide(self):
+    def test_open_slide(self) -> None:
         with open_slide(file_path('boxes.tiff')) as osr:
             self.assertTrue(isinstance(osr, OpenSlide))
         with open_slide(file_path('boxes.png')) as osr:
             self.assertTrue(isinstance(osr, ImageSlide))
 
-    def test_lowlevel_available(self):
+    def test_lowlevel_available(self) -> None:
         '''Ensure all exported functions have an 'available' attribute.'''
         for name in dir(lowlevel):
             attr = getattr(lowlevel, name)
diff --git a/tests/test_deepzoom.py b/tests/test_deepzoom.py
index af1cd503..1c67ab06 100644
--- a/tests/test_deepzoom.py
+++ b/tests/test_deepzoom.py
@@ -27,90 +27,97 @@
 from openslide.deepzoom import DeepZoomGenerator
 
 
-class _BoxesDeepZoomTest:
-    def setUp(self):
-        self.osr = self.CLASS(file_path(self.FILENAME))
-        self.dz = DeepZoomGenerator(self.osr, 254, 1)
-
-    def tearDown(self):
-        self.osr.close()
-
-    def test_repr(self):
-        self.assertEqual(
-            repr(self.dz),
-            ('DeepZoomGenerator(%r, tile_size=254, overlap=1, ' + 'limit_bounds=False)')
-            % self.osr,
-        )
-
-    def test_metadata(self):
-        self.assertEqual(self.dz.level_count, 10)
-        self.assertEqual(self.dz.tile_count, 11)
-        self.assertEqual(
-            self.dz.level_tiles,
-            (
-                (1, 1),
-                (1, 1),
-                (1, 1),
-                (1, 1),
-                (1, 1),
-                (1, 1),
-                (1, 1),
-                (1, 1),
-                (1, 1),
-                (2, 1),
-            ),
-        )
-        self.assertEqual(
-            self.dz.level_dimensions,
-            (
-                (1, 1),
-                (2, 1),
-                (3, 2),
-                (5, 4),
-                (10, 8),
-                (19, 16),
-                (38, 32),
-                (75, 63),
-                (150, 125),
-                (300, 250),
-            ),
-        )
-
-    def test_get_tile(self):
-        self.assertEqual(self.dz.get_tile(9, (1, 0)).size, (47, 250))
-
-    def test_tile_color_profile(self):
-        if self.CLASS is OpenSlide and not lowlevel.read_icc_profile.available:
-            self.skipTest("requires OpenSlide 4.0.0")
-        self.assertEqual(len(self.dz.get_tile(9, (1, 0)).info['icc_profile']), 588)
-
-    def test_get_tile_bad_level(self):
-        self.assertRaises(ValueError, lambda: self.dz.get_tile(-1, (0, 0)))
-        self.assertRaises(ValueError, lambda: self.dz.get_tile(10, (0, 0)))
-
-    def test_get_tile_bad_address(self):
-        self.assertRaises(ValueError, lambda: self.dz.get_tile(0, (-1, 0)))
-        self.assertRaises(ValueError, lambda: self.dz.get_tile(0, (1, 0)))
-
-    def test_get_tile_coordinates(self):
-        self.assertEqual(
-            self.dz.get_tile_coordinates(9, (1, 0)), ((253, 0), 0, (47, 250))
-        )
-
-    def test_get_tile_dimensions(self):
-        self.assertEqual(self.dz.get_tile_dimensions(9, (1, 0)), (47, 250))
-
-    def test_get_dzi(self):
-        self.assertTrue(
-            'http://schemas.microsoft.com/deepzoom/2008' in self.dz.get_dzi('jpeg')
-        )
-
-
-class TestSlideDeepZoom(_BoxesDeepZoomTest, unittest.TestCase):
+class _Abstract:
+    # nested class to prevent the test runner from finding it
+    class BoxesDeepZoomTest(unittest.TestCase):
+        CLASS: type | None = None
+        FILENAME: str | None = None
+
+        def setUp(self) -> None:
+            assert self.CLASS is not None
+            assert self.FILENAME is not None
+            self.osr = self.CLASS(file_path(self.FILENAME))
+            self.dz = DeepZoomGenerator(self.osr, 254, 1)
+
+        def tearDown(self) -> None:
+            self.osr.close()
+
+        def test_repr(self) -> None:
+            self.assertEqual(
+                repr(self.dz),
+                'DeepZoomGenerator(%r, tile_size=254, overlap=1, limit_bounds=False)'
+                % self.osr,
+            )
+
+        def test_metadata(self) -> None:
+            self.assertEqual(self.dz.level_count, 10)
+            self.assertEqual(self.dz.tile_count, 11)
+            self.assertEqual(
+                self.dz.level_tiles,
+                (
+                    (1, 1),
+                    (1, 1),
+                    (1, 1),
+                    (1, 1),
+                    (1, 1),
+                    (1, 1),
+                    (1, 1),
+                    (1, 1),
+                    (1, 1),
+                    (2, 1),
+                ),
+            )
+            self.assertEqual(
+                self.dz.level_dimensions,
+                (
+                    (1, 1),
+                    (2, 1),
+                    (3, 2),
+                    (5, 4),
+                    (10, 8),
+                    (19, 16),
+                    (38, 32),
+                    (75, 63),
+                    (150, 125),
+                    (300, 250),
+                ),
+            )
+
+        def test_get_tile(self) -> None:
+            self.assertEqual(self.dz.get_tile(9, (1, 0)).size, (47, 250))
+
+        def test_tile_color_profile(self) -> None:
+            if self.CLASS is OpenSlide and not lowlevel.read_icc_profile.available:
+                self.skipTest("requires OpenSlide 4.0.0")
+            self.assertEqual(len(self.dz.get_tile(9, (1, 0)).info['icc_profile']), 588)
+
+        def test_get_tile_bad_level(self) -> None:
+            self.assertRaises(ValueError, lambda: self.dz.get_tile(-1, (0, 0)))
+            self.assertRaises(ValueError, lambda: self.dz.get_tile(10, (0, 0)))
+
+        def test_get_tile_bad_address(self) -> None:
+            self.assertRaises(ValueError, lambda: self.dz.get_tile(0, (-1, 0)))
+            self.assertRaises(ValueError, lambda: self.dz.get_tile(0, (1, 0)))
+
+        def test_get_tile_coordinates(self) -> None:
+            self.assertEqual(
+                self.dz.get_tile_coordinates(9, (1, 0)), ((253, 0), 0, (47, 250))
+            )
+
+        def test_get_tile_dimensions(self) -> None:
+            self.assertEqual(self.dz.get_tile_dimensions(9, (1, 0)), (47, 250))
+
+        def test_get_dzi(self) -> None:
+            self.assertTrue(
+                'http://schemas.microsoft.com/deepzoom/2008' in self.dz.get_dzi('jpeg')
+            )
+
+
+class TestSlideDeepZoom(_Abstract.BoxesDeepZoomTest):
     CLASS = OpenSlide
     FILENAME = 'boxes.tiff'
 
 
-class TestImageDeepZoom(_BoxesDeepZoomTest, unittest.TestCase):
+class TestImageDeepZoom(_Abstract.BoxesDeepZoomTest):
     CLASS = ImageSlide
     FILENAME = 'boxes.png'
diff --git a/tests/test_imageslide.py b/tests/test_imageslide.py
index e577851f..051263ee 100644
--- a/tests/test_imageslide.py
+++ b/tests/test_imageslide.py
@@ -29,16 +29,16 @@
 
 
 class TestImageWithoutOpening(unittest.TestCase):
-    def test_detect_format(self):
+    def test_detect_format(self) -> None:
         self.assertTrue(ImageSlide.detect_format(file_path('__missing_file')) is None)
         self.assertTrue(ImageSlide.detect_format(file_path('../setup.py')) is None)
         self.assertEqual(ImageSlide.detect_format(file_path('boxes.png')), 'PNG')
 
-    def test_open(self):
+    def test_open(self) -> None:
         self.assertRaises(OSError, lambda: ImageSlide(file_path('__does_not_exist')))
         self.assertRaises(OSError, lambda: ImageSlide(file_path('../setup.py')))
 
-    def test_open_image(self):
+    def test_open_image(self) -> None:
         # passing PIL.Image to ImageSlide
         with Image.open(file_path('boxes.png')) as img:
             with ImageSlide(img) as osr:
@@ -49,18 +49,18 @@ def test_open_image(self):
         sys.getfilesystemencoding() == 'utf-8',
         'Python filesystem encoding is not UTF-8',
     )
-    def test_unicode_path(self):
+    def test_unicode_path(self) -> None:
         path = file_path('😐.png')
         for arg in path, str(path):
             self.assertEqual(ImageSlide.detect_format(arg), 'PNG')
             self.assertEqual(ImageSlide(arg).dimensions, (300, 250))
 
-    def test_unicode_path_bytes(self):
+    def test_unicode_path_bytes(self) -> None:
         arg = str(file_path('😐.png')).encode('UTF-8')
         self.assertEqual(ImageSlide.detect_format(arg), 'PNG')
         self.assertEqual(ImageSlide(arg).dimensions, (300, 250))
 
-    def test_operations_on_closed_handle(self):
+    def test_operations_on_closed_handle(self) -> None:
         with Image.open(file_path('boxes.png')) as img:
             osr = ImageSlide(img)
             osr.close()
@@ -72,7 +72,7 @@ def test_operations_on_closed_handle(self):
             # shouldn't close it
             self.assertEqual(img.getpixel((0, 0)), 3)
 
-    def test_context_manager(self):
+    def test_context_manager(self) -> None:
         osr = ImageSlide(file_path('boxes.png'))
         with osr:
             pass
@@ -80,21 +80,26 @@ def test_context_manager(self):
         self.assertRaises(ValueError, lambda: osr.level_dimensions)
 
 
-class _SlideTest:
-    def setUp(self):
-        self.osr = ImageSlide(file_path(self.FILENAME))
+class _Abstract:
+    # nested class to prevent the test runner from finding it
+    class SlideTest(unittest.TestCase):
+        FILENAME: str | None = None
 
-    def tearDown(self):
-        self.osr.close()
+        def setUp(self) -> None:
+            assert self.FILENAME is not None
+            self.osr = ImageSlide(file_path(self.FILENAME))
 
+        def tearDown(self) -> None:
+            self.osr.close()
 
-class TestImage(_SlideTest, unittest.TestCase):
+
+class TestImage(_Abstract.SlideTest):
     FILENAME = 'boxes.png'
 
-    def test_repr(self):
+    def test_repr(self) -> None:
         self.assertEqual(repr(self.osr), 'ImageSlide(%r)' % file_path('boxes.png'))
 
-    def test_metadata(self):
+    def test_metadata(self) -> None:
         self.assertEqual(self.osr.level_count, 1)
         self.assertEqual(self.osr.level_dimensions, ((300, 250),))
         self.assertEqual(self.osr.dimensions, (300, 250))
@@ -106,7 +111,8 @@ def test_metadata(self):
         self.assertEqual(self.osr.properties, {})
         self.assertEqual(self.osr.associated_images, {})
 
-    def test_color_profile(self):
+    def test_color_profile(self) -> None:
+        assert self.osr.color_profile is not None  # for type inference
         self.assertEqual(self.osr.color_profile.profile.device_class, 'mntr')
         self.assertEqual(
             len(self.osr.read_region((0, 0), 0, (100, 100)).info['icc_profile']), 588
@@ -115,37 +121,37 @@ def test_color_profile(self):
             len(self.osr.get_thumbnail((100, 100)).info['icc_profile']), 588
         )
 
-    def test_read_region(self):
+    def test_read_region(self) -> None:
         self.assertEqual(
             self.osr.read_region((-10, -10), 0, (400, 400)).size, (400, 400)
         )
 
-    def test_read_region_size_dimension_zero(self):
+    def test_read_region_size_dimension_zero(self) -> None:
         self.assertEqual(self.osr.read_region((0, 0), 0, (400, 0)).size, (400, 0))
 
-    def test_read_region_bad_level(self):
+    def test_read_region_bad_level(self) -> None:
         self.assertRaises(
             OpenSlideError, lambda: self.osr.read_region((0, 0), 1, (100, 100))
         )
 
-    def test_read_region_bad_size(self):
+    def test_read_region_bad_size(self) -> None:
         self.assertRaises(
             OpenSlideError, lambda: self.osr.read_region((0, 0), 0, (400, -5))
         )
 
-    def test_thumbnail(self):
+    def test_thumbnail(self) -> None:
         self.assertEqual(self.osr.get_thumbnail((100, 100)).size, (100, 83))
 
     @unittest.skipUnless(lowlevel.cache_create.available, "requires OpenSlide 4.0.0")
-    def test_set_cache(self):
+    def test_set_cache(self) -> None:
         self.osr.set_cache(OpenSlideCache(64 << 10))
         self.assertEqual(self.osr.read_region((0, 0), 0, (400, 400)).size, (400, 400))
 
 
-class TestNoIccImage(_SlideTest, unittest.TestCase):
+class TestNoIccImage(_Abstract.SlideTest):
     FILENAME = 'boxes-no-icc.png'
 
-    def test_color_profile(self):
+    def test_color_profile(self) -> None:
         self.assertIsNone(self.osr.color_profile)
         self.assertNotIn(
             'icc_profile', self.osr.read_region((0, 0), 0, (100, 100)).info
diff --git a/tests/test_openslide.py b/tests/test_openslide.py
index b863fb97..2be656fd 100644
--- a/tests/test_openslide.py
+++ b/tests/test_openslide.py
@@ -22,6 +22,7 @@
 from ctypes import ArgumentError
 import re
 import sys
+from typing import Any
 import unittest
 
 from common import file_path
@@ -37,31 +38,39 @@
 
 class TestCache(unittest.TestCase):
     @unittest.skipUnless(lowlevel.cache_create.available, "requires OpenSlide 4.0.0")
-    def test_create_cache(self):
+    def test_create_cache(self) -> None:
         OpenSlideCache(0)
         OpenSlideCache(1)
         OpenSlideCache(4 << 20)
         self.assertRaises(ArgumentError, lambda: OpenSlideCache(-1))
-        self.assertRaises(ArgumentError, lambda: OpenSlideCache(1.3))
+        self.assertRaises(
+            ArgumentError, lambda: OpenSlideCache(1.3)  # type: ignore[arg-type]
+        )
 
 
 class TestSlideWithoutOpening(unittest.TestCase):
-    def test_detect_format(self):
+    def test_detect_format(self) -> None:
         self.assertTrue(OpenSlide.detect_format(file_path('__missing_file')) is None)
         self.assertTrue(OpenSlide.detect_format(file_path('../setup.py')) is None)
         self.assertEqual(
             OpenSlide.detect_format(file_path('boxes.tiff')), 'generic-tiff'
         )
 
-    def test_open(self):
+    def test_open(self) -> None:
         self.assertRaises(
             OpenSlideUnsupportedFormatError, lambda: OpenSlide('__does_not_exist')
         )
         self.assertRaises(
             OpenSlideUnsupportedFormatError, lambda: OpenSlide('setup.py')
         )
-        self.assertRaises(ArgumentError, lambda: OpenSlide(None))
-        self.assertRaises(ArgumentError, lambda: OpenSlide(3))
+        self.assertRaises(
+            ArgumentError,
+            lambda: OpenSlide(None),  # type: ignore[arg-type]
+        )
+        self.assertRaises(
+            ArgumentError,
+            lambda: OpenSlide(3),  # type: ignore[arg-type]
+        )
         self.assertRaises(
             OpenSlideUnsupportedFormatError, lambda: OpenSlide('unopenable.tiff')
         )
@@ -70,18 +79,18 @@ def test_open(self):
         sys.getfilesystemencoding() == 'utf-8',
         'Python filesystem encoding is not UTF-8',
     )
-    def test_unicode_path(self):
+    def test_unicode_path(self) -> None:
         path = file_path('😐.svs')
         for arg in path, str(path):
             self.assertEqual(OpenSlide.detect_format(arg), 'aperio')
             self.assertEqual(OpenSlide(arg).dimensions, (16, 16))
 
-    def test_unicode_path_bytes(self):
+    def test_unicode_path_bytes(self) -> None:
         arg = str(file_path('😐.svs')).encode('UTF-8')
         self.assertEqual(OpenSlide.detect_format(arg), 'aperio')
         self.assertEqual(OpenSlide(arg).dimensions, (16, 16))
 
-    def test_operations_on_closed_handle(self):
+    def test_operations_on_closed_handle(self) -> None:
         osr = OpenSlide(file_path('boxes.tiff'))
         props = osr.properties
         associated = osr.associated_images
@@ -91,28 +100,33 @@ def test_operations_on_closed_handle(self):
         self.assertRaises(ArgumentError, lambda: props['openslide.vendor'])
         self.assertRaises(ArgumentError, lambda: associated['label'])
 
-    def test_context_manager(self):
+    def test_context_manager(self) -> None:
         osr = OpenSlide(file_path('boxes.tiff'))
         with osr:
             self.assertEqual(osr.level_count, 4)
         self.assertRaises(ArgumentError, lambda: osr.level_count)
 
 
-class _SlideTest:
-    def setUp(self):
-        self.osr = OpenSlide(file_path(self.FILENAME))
+class _Abstract:
+    # nested class to prevent the test runner from finding it
+    class SlideTest(unittest.TestCase):
+        FILENAME: str | None = None
 
-    def tearDown(self):
-        self.osr.close()
+        def setUp(self) -> None:
+            assert self.FILENAME is not None
+            self.osr = OpenSlide(file_path(self.FILENAME))
 
+        def tearDown(self) -> None:
+            self.osr.close()
 
-class TestSlide(_SlideTest, unittest.TestCase):
+
+class TestSlide(_Abstract.SlideTest):
     FILENAME = 'boxes.tiff'
 
-    def test_repr(self):
+    def test_repr(self) -> None:
         self.assertEqual(repr(self.osr), 'OpenSlide(%r)' % file_path('boxes.tiff'))
 
-    def test_basic_metadata(self):
+    def test_basic_metadata(self) -> None:
         self.assertEqual(self.osr.level_count, 4)
         self.assertEqual(
             self.osr.level_dimensions, ((300, 250), (150, 125), (75, 62), (37, 31))
@@ -128,7 +142,7 @@ def test_basic_metadata(self):
         self.assertEqual(self.osr.get_best_level_for_downsample(3), 1)
         self.assertEqual(self.osr.get_best_level_for_downsample(37), 3)
 
-    def test_properties(self):
+    def test_properties(self) -> None:
         self.assertEqual(self.osr.properties['openslide.vendor'], 'generic-tiff')
         self.assertRaises(KeyError, lambda: self.osr.properties['__does_not_exist'])
         # test __len__ and __iter__
@@ -142,7 +156,8 @@ def test_properties(self):
     @unittest.skipUnless(
         lowlevel.read_icc_profile.available, "requires OpenSlide 4.0.0"
     )
-    def test_color_profile(self):
+    def test_color_profile(self) -> None:
+        assert self.osr.color_profile is not None  # for type inference
         self.assertEqual(self.osr.color_profile.profile.device_class, 'mntr')
         self.assertEqual(
             len(self.osr.read_region((0, 0), 0, (100, 100)).info['icc_profile']), 588
@@ -151,18 +166,18 @@ def test_color_profile(self):
             len(self.osr.get_thumbnail((100, 100)).info['icc_profile']), 588
         )
 
-    def test_read_region(self):
+    def test_read_region(self) -> None:
         self.assertEqual(
             self.osr.read_region((-10, -10), 1, (400, 400)).size, (400, 400)
         )
 
-    def test_read_region_size_dimension_zero(self):
+    def test_read_region_size_dimension_zero(self) -> None:
         self.assertEqual(self.osr.read_region((0, 0), 1, (400, 0)).size, (400, 0))
 
-    def test_read_region_bad_level(self):
+    def test_read_region_bad_level(self) -> None:
         self.assertEqual(self.osr.read_region((0, 0), 4, (100, 100)).size, (100, 100))
 
-    def test_read_region_bad_size(self):
+    def test_read_region_bad_size(self) -> None:
         self.assertRaises(
             OpenSlideError, lambda: self.osr.read_region((0, 0), 1, (400, -5))
         )
@@ -170,26 +185,30 @@ def test_read_region_bad_size(self):
     @unittest.skipIf(sys.maxsize < 1 << 32, '32-bit Python')
     # Disabled to avoid OOM killer on small systems, since the stdlib
     # doesn't provide a way to find out how much RAM we have
-    def _test_read_region_2GB(self):
+    def _test_read_region_2GB(self) -> None:
         self.assertEqual(
             self.osr.read_region((1000, 1000), 0, (32768, 16384)).size, (32768, 16384)
         )
 
-    def test_thumbnail(self):
+    def test_thumbnail(self) -> None:
         self.assertEqual(self.osr.get_thumbnail((100, 100)).size, (100, 83))
 
     @unittest.skipUnless(lowlevel.cache_create.available, "requires OpenSlide 4.0.0")
-    def test_set_cache(self):
+    def test_set_cache(self) -> None:
         self.osr.set_cache(OpenSlideCache(64 << 10))
         self.assertEqual(self.osr.read_region((0, 0), 0, (400, 400)).size, (400, 400))
-        self.assertRaises(TypeError, lambda: self.osr.set_cache(None))
-        self.assertRaises(TypeError, lambda: self.osr.set_cache(3))
+        self.assertRaises(
+            TypeError, lambda: self.osr.set_cache(None)  # type: ignore[arg-type]
+        )
+        self.assertRaises(
+            TypeError, lambda: self.osr.set_cache(3)  # type: ignore[arg-type]
+        )
 
 
-class TestAperioSlide(_SlideTest, unittest.TestCase):
+class TestAperioSlide(_Abstract.SlideTest):
     FILENAME = 'small.svs'
 
-    def test_associated_images(self):
+    def test_associated_images(self) -> None:
         self.assertEqual(self.osr.associated_images['thumbnail'].size, (16, 16))
         self.assertRaises(KeyError, lambda: self.osr.associated_images['__missing'])
         # test __len__ and __iter__
@@ -198,7 +217,7 @@ def test_associated_images(self):
             len(self.osr.associated_images),
         )
 
-        def mangle_repr(o):
+        def mangle_repr(o: Any) -> str:
             return re.sub('0x[0-9a-fA-F]+', '(mangled)', repr(o))
 
         self.assertEqual(
@@ -206,7 +225,7 @@ def mangle_repr(o):
             '<_AssociatedImageMap %s>' % mangle_repr(dict(self.osr.associated_images)),
         )
 
-    def test_color_profile(self):
+    def test_color_profile(self) -> None:
         self.assertIsNone(self.osr.color_profile)
         self.assertNotIn(
             'icc_profile', self.osr.read_region((0, 0), 0, (100, 100)).info
@@ -220,10 +239,11 @@ def test_color_profile(self):
 @unittest.skipUnless(
     lowlevel.read_associated_image_icc_profile.available, "requires OpenSlide 4.0.0"
 )
-class TestDicomSlide(_SlideTest, unittest.TestCase):
+class TestDicomSlide(_Abstract.SlideTest):
     FILENAME = 'boxes_0.dcm'
 
-    def test_color_profile(self):
+    def test_color_profile(self) -> None:
+        assert self.osr.color_profile is not None  # for type inference
         self.assertEqual(self.osr.color_profile.profile.device_class, 'mntr')
         main_profile = self.osr.read_region((0, 0), 0, (100, 100)).info['icc_profile']
         associated_profile = self.osr.associated_images['thumbnail'].info['icc_profile']
@@ -232,10 +252,10 @@ def test_color_profile(self):
         self.assertIs(main_profile, associated_profile)
 
 
-class TestUnreadableSlide(_SlideTest, unittest.TestCase):
+class TestUnreadableSlide(_Abstract.SlideTest):
     FILENAME = 'unreadable.svs'
 
-    def test_read_bad_region(self):
+    def test_read_bad_region(self) -> None:
         self.assertEqual(self.osr.properties['openslide.vendor'], 'aperio')
         self.assertRaises(
             OpenSlideError, lambda: self.osr.read_region((0, 0), 0, (16, 16))
@@ -245,7 +265,7 @@ def test_read_bad_region(self):
             OpenSlideError, lambda: self.osr.properties['openslide.vendor']
         )
 
-    def test_read_bad_associated_image(self):
+    def test_read_bad_associated_image(self) -> None:
         self.assertEqual(self.osr.properties['openslide.vendor'], 'aperio')
         # Prints "JPEGLib: Bogus marker length." to stderr due to
         # https://github.com/openslide/openslide/issues/36