diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index ff2445b..62b09e6 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -2,7 +2,7 @@
 name: CI
 
 on:
-  push:
+  push: ~
 
 jobs:
   build:
@@ -12,20 +12,44 @@ jobs:
         python-version:
           # Note: Use quotes to avoid float cast - especially important if the
           # version number ends with 0!
-          - "3.9"
           - "3.10"
           - "3.11"
+          - "3.12"
 
     steps:
-      - name: Clone Repo
+      - name: Clone repo
         uses: actions/checkout@v3
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v4
         with:
+          # https://github.com/actions/setup-python#caching-packages-dependencies
+          cache: pip
           python-version: ${{ matrix.python-version }}
-      - name: Install Dependencies
+      - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
           pip install .
-      - name: Run Tests
+      - name: Run tests
         run: python -m unittest
+
+  docs:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Clone repo
+        uses: actions/checkout@v3
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          # https://github.com/actions/setup-python#caching-packages-dependencies
+          cache: pip
+          python-version: "3.12"
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install .[docs-builder]
+      - name: Check docs build
+        run: |
+          cd docs
+          mkdir -p _static
+          make html
diff --git a/.readthedocs.yaml b/.readthedocs.yaml
new file mode 100644
index 0000000..f449c8b
--- /dev/null
+++ b/.readthedocs.yaml
@@ -0,0 +1,14 @@
+# https://docs.readthedocs.io/en/stable/config-file/v2.html
+version: 2
+
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
+python:
+  install:
+    - requirements: docs/requirements.txt
+
+sphinx:
+  configuration: docs/conf.py
diff --git a/README.rst b/README.rst
index 97481b2..997662c 100644
--- a/README.rst
+++ b/README.rst
@@ -1,3 +1,5 @@
+.. image:: https://github.com/todofixthis/filters/actions/workflows/build.yml/badge.svg
+   :target: https://github.com/todofixthis/filters/actions/workflows/build.yml
 .. image:: https://readthedocs.org/projects/filters/badge/?version=latest
    :target: http://filters.readthedocs.io/
 
@@ -14,8 +16,8 @@ data validation and processing pipelines, including:
 
 And much more!
 
-The output from one filter can be "piped" into the input of another, enabling
-you to "chain" filters together to quickly and easily create complex data
+The output from one filter can be piped into the input of another, enabling you
+to chain filters together to quickly and easily create complex data schemas and
 pipelines.
 
 
@@ -62,7 +64,7 @@ Parse a JSON string and check that it has correct structure:
        f.FilterMapper(
            {
                'birthday':  f.Date,
-               'gender':    f.CaseFold | f.Choice(choices={'m', 'f', 'x'}),
+               'gender':    f.CaseFold | f.Choice(choices={'f', 'm', 'n'}),
 
                'utcOffset':
                    f.Decimal |
@@ -81,9 +83,9 @@ Requirements
 ------------
 Filters is known to be compatible with the following Python versions:
 
+- 3.12
 - 3.11
 - 3.10
-- 3.9
 
 .. note::
    I'm only one person, so to keep from getting overwhelmed, I'm only committing
diff --git a/docs/index.rst b/docs/index.rst
index ac8736c..8dd2622 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -90,9 +90,9 @@ Requirements
 ------------
 Filters is known to be compatible with the following Python versions:
 
+* 3.12
 * 3.11
 * 3.10
-* 3.9
 
 .. note::
    I'm only one person, so to keep from getting overwhelmed, I'm only committing
diff --git a/docs/requirements.txt b/docs/requirements.txt
new file mode 100644
index 0000000..cdf642b
--- /dev/null
+++ b/docs/requirements.txt
@@ -0,0 +1,3 @@
+# https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html#id6
+sphinx
+sphinx_rtd_theme
diff --git a/filters/__init__.py b/filters/__init__.py
index 150ca71..3a4a5d1 100644
--- a/filters/__init__.py
+++ b/filters/__init__.py
@@ -1,8 +1,3 @@
-# http://stackoverflow.com/a/2073599/
-from pkg_resources import require
-__version__ = require('phx-filters')[0].version
-del require
-
 # Make the base filters accessible from the top level of the package.
 # Note that the order is important here, due to dependencies.
 from .base import *
diff --git a/filters/extensions.py b/filters/extensions.py
index 87b602a..2aab025 100644
--- a/filters/extensions.py
+++ b/filters/extensions.py
@@ -1,10 +1,10 @@
 import typing
+from importlib.metadata import EntryPoint, entry_points
 from inspect import getmembers as get_members, isabstract as is_abstract, \
     isclass as is_class, ismodule as is_module
 from logging import getLogger
 
 from class_registry import EntryPointClassRegistry
-from pkg_resources import EntryPoint, iter_entry_points
 
 from filters.base import BaseFilter
 
@@ -49,6 +49,11 @@ def __init__(self, group: str = GROUP_NAME) -> None:
         super().__init__(group)
 
     def __getattr__(self, item: str) -> typing.Type[BaseFilter]:
+        """
+        Provides attr-like interface for accessing extension filters (the
+        default interface for class registries is to access items rather than
+        attributes).
+        """
         return self[item]
 
     def __repr__(self):
@@ -58,8 +63,7 @@ def _get_cache(self) -> typing.Dict[str, typing.Type[BaseFilter]]:
         if self._cache is None:
             self._cache = {}
 
-            for target in iter_entry_points(
-                    self.group):  # type: EntryPoint
+            for target in entry_points(group=self.group):  # type: EntryPoint
                 filter_ = target.load()
 
                 ift_result = is_filter_type(filter_)
diff --git a/pyproject.toml b/pyproject.toml
index c8ce2a3..7879d7b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,10 +2,10 @@
 
 [project]
 name = "phx-filters"
-version = "3.3.0"
+version = "3.4.0"
 description = "Validation and data pipelines made easy!"
 readme = "README.rst"
-requires-python = ">= 3.6"
+requires-python = ">= 3.10"
 license = { file = "LICENCE.txt" }
 authors = [
     { email = "Phoenix Zerin <phx@phx.nz>" }
@@ -23,16 +23,16 @@ classifiers = [
     "Intended Audience :: Developers",
     "License :: OSI Approved :: MIT License",
     "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.10",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: Implementation :: PyPy",
     "Topic :: Software Development :: Libraries :: Python Modules",
     'Topic :: Text Processing :: Filters',
 ]
 
 dependencies = [
-    "phx-class-registry",
+    "phx-class-registry >= 4.1.0",
     "python-dateutil",
     "pytz",
     "regex >= 2018.8.17",
diff --git a/test/helper.py b/test/helper.py
new file mode 100644
index 0000000..9737cc8
--- /dev/null
+++ b/test/helper.py
@@ -0,0 +1,41 @@
+import sys
+from importlib.metadata import DistributionFinder, PathDistribution
+from os import path
+from pathlib import Path
+
+
+class DummyDistributionFinder(DistributionFinder):
+    """
+    Injects a dummy distribution into the meta path finder, so that we can
+    pretend like it's been pip installed during unit tests (i.e., so that we
+    can test ``FilterExtensionRegistry``), without polluting the persistent
+    virtualenv.
+    """
+
+    DUMMY_PACKAGE_DIR = 'filter_extension.egg-info'
+
+    @classmethod
+    def install(cls):
+        for finder in sys.meta_path:
+            if isinstance(finder, cls):
+                # If we've already installed an instance of the class, then
+                # something is probably wrong with our tests.
+                raise ValueError(f'{cls.__name__} is already installed')
+
+        sys.meta_path.append(cls())
+
+    @classmethod
+    def uninstall(cls):
+        for i, finder in enumerate(sys.meta_path):
+            if isinstance(finder, cls):
+                sys.meta_path.pop(i)
+                return
+        else:
+            # If we didn't find an installed instance of the class, then
+            # something is probably wrong with our tests.
+            raise ValueError(f'{cls.__name__} was not installed')
+
+    def find_distributions(self, context=...) -> list[PathDistribution]:
+        return [PathDistribution(
+            Path(path.join(path.dirname(__file__), self.DUMMY_PACKAGE_DIR))
+        )]
diff --git a/test/test_extensions.py b/test/test_extensions.py
index ed94f31..2bbae24 100644
--- a/test/test_extensions.py
+++ b/test/test_extensions.py
@@ -1,23 +1,18 @@
-from os.path import dirname
 from unittest import TestCase
 
-from pkg_resources import working_set
-
 from filters.extensions import FilterExtensionRegistry
 from filters.macros import FilterMacroType
 from test import TestFilterAlpha, TestFilterBravo
+from test.helper import DummyDistributionFinder
 
 
 def setUpModule():
-    #
-    # Install a fake distribution that we can use to inject entry
-    # points at runtime.
-    #
-    # The side effects from this are pretty severe, but they (very
-    # probably) only impact this test, and they are undone as soon as
-    # the process terminates.
-    #
-    working_set.add_entry(dirname(__file__))
+    # Inject a distribution that defines some entry points.
+    DummyDistributionFinder.install()
+
+
+def tearDownModule():
+    DummyDistributionFinder.uninstall()
 
 
 class FilterExtensionRegistryTestCase(TestCase):
diff --git a/test/test_string.py b/test/test_string.py
index 5e57dc3..5dc0dcf 100644
--- a/test/test_string.py
+++ b/test/test_string.py
@@ -1290,7 +1290,7 @@ def test_fail_no_match(self):
 
     def test_pass_unicode_character_class(self):
         """
-        By default, character classes like ``\w`` will take unicode into
+        By default, character classes like ``\\w`` will take unicode into
         account.
         """
         # "Hi, there!" in Japanese, according to the internet :innocent:
@@ -1382,7 +1382,7 @@ def test_pass_pattern_split(self):
         You can also use a regex to split the string.
         """
         self.assertFilterPasses(
-            self._filter('foo-12-bar-34-baz', pattern='[-\d]+'),
+            self._filter('foo-12-bar-34-baz', pattern=r'[-\d]+'),
             ['foo', 'bar', 'baz'],
         )
 
@@ -1393,7 +1393,7 @@ def test_pass_pattern_split_with_groups(self):
         """
         self.assertFilterPasses(
             # Note grouping parentheses in the regex.
-            self._filter('foo-12-bar-34-baz', pattern='([-\d]+)'),
+            self._filter('foo-12-bar-34-baz', pattern=r'([-\d]+)'),
             ['foo', '-12-', 'bar', '-34-', 'baz'],
         )
 
@@ -1405,7 +1405,7 @@ def test_pass_no_split(self):
         parts.
         """
         self.assertFilterPasses(
-            self._filter('foo:bar:baz', pattern='[-\d]+'),
+            self._filter('foo:bar:baz', pattern=r'[-\d]+'),
             ['foo:bar:baz'],
         )
 
@@ -1659,7 +1659,7 @@ def test_pass_curly_hex(self):
         """
         You can include curly braces around hex values.
 
-        Use ``Regex(r'^[\da-f]+$') | Uuid`` if you only want to allow plain
+        Use ``Regex(r'^[\\da-f]+$') | Uuid`` if you only want to allow plain
         hex.
         """
         filtered = self._filter('{54d6ebf8a3f55ed59becdedfb3b0773f}')
@@ -1678,7 +1678,7 @@ def test_pass_urn(self):
         antiquated, but still valid.
 
         If you want to prohibit URNs, chain this filter with
-        ``Regex(r'^[\da-f]+$')``.
+        ``Regex(r'^[\\da-f]+$')``.
 
         References:
 
@@ -1764,7 +1764,7 @@ def test_pass_unicode(self):
         """
         The incoming value is a unicode.
         """
-        self.assertFilterPasses('┻━┻︵ \(°□°)/ ︵ ┻━┻ ')  # RAWR!
+        self.assertFilterPasses(r'┻━┻︵ \(°□°)/ ︵ ┻━┻ ')  # RAWR!
 
     def test_pass_bytes_utf8(self):
         """
diff --git a/tox.ini b/tox.ini
index aefb8bb..fb2d97e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py3{11,10,9}
+envlist = py3{12,11,10}
 
 [testenv]
 commands = python -m unittest