diff --git a/.gitignore b/.gitignore
index 1d465a2..0a2761c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,14 +1,150 @@
-*.swp
+# Project-specific generated files
+docs/build/
+
+# Temp file during Mypy processing
+mypy_annotate.dat
 
-/.pytest_cache/
-/.coverage
-/.cache/
-/.eggs/
-/.pybuild/
-/build/
-/docs/build/
-__pycache__/
-/trio_asyncio.egg-info/
-/.pybuild/
-/dist
 /empty
+
+# MacOS files
+**/.DS_Store
+
+# Byte-compiled / optimized / DLL files / editor temp files
+__pycache__/
+*.py[cod]
+*$py.class
+*~
+\#*
+.#*
+*.swp
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+pip-wheel-metadata/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+pip-wheel-metadata/
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+pyvenv.cfg
+.venv/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+*.py,cover
+.hypothesis/
+.pytest_cache/
+.mypy_cache/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+db.sqlite3-journal
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# pyenv
+.python-version
+
+# pipenv
+#   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
+#   However, in case of collaboration, if having platform-specific dependencies or dependencies
+#   having no cross-platform support, pipenv may install dependencies that don't work, or not
+#   install all needed dependencies.
+#Pipfile.lock
+
+# PEP 582; used by e.g. github.com/David-OConnor/pyflow
+__pypackages__/
+
+# Celery stuff
+celerybeat-schedule
+celerybeat.pid
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/
+
+# Ruff
+.ruff_cache
+
+# Sphinx documentation
+doc/_build/
+
+# PyCharm
+.idea/
diff --git a/CHEATSHEET.rst b/CHEATSHEET.rst
index 2deead4..7328447 100644
--- a/CHEATSHEET.rst
+++ b/CHEATSHEET.rst
@@ -14,12 +14,12 @@ To run yapf
 -----------
 
 * Show what changes yapf wants to make:
-  ``yapf3 -rpd setup.py trio_asyncio tests``
+  ``yapf3 -rpd trio_asyncio tests``
 
 * Apply all changes directly to the source tree:
-  ``yapf -rpi setup.py trio_asyncio tests``
+  ``yapf -rpi trio_asyncio tests``
 
-* Find semantic problems: ``flake8 setup.py trio_asyncio tests``
+* Find semantic problems: ``flake8 trio_asyncio tests``
 
 
 To make a release
diff --git a/Makefile b/Makefile
index 9079954..cf8af7b 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@
 .PHONY: doc test update all tag pypi upload
 
 all:
-		@echo "Please use 'python setup.py'."
+		@echo "Please use 'pip install -e .'."
 		@exit 1
 
 # need to use python3 sphinx-build
@@ -43,12 +43,14 @@ test:
 
 
 tag:
-		@-git tag v$(shell python3 setup.py -V)
+		@-git tag v$(shell python3 -c "from trio_asyncio._version import __version__; print(__version__)")
 
 pypi:   tag
-	@if python3 setup.py -V 2>/dev/null | grep -qs + >/dev/null 2>&1 ; \
+	@if python3 python3 -c "from trio_asyncio._version import __version__; print(__version__)" 2>/dev/null | grep -qs + >/dev/null 2>&1 ; \
 		then echo "You need a clean, tagged tree" >&2; exit 1 ; fi
-	python3 setup.py sdist upload
+	python3 -m pip install uv
+	uv build
+	uv publish
 	## version depends on tag, so re-tagging doesn't make sense
 
 upload: pypi
diff --git a/ci.sh b/ci.sh
index ba194d6..5587fd0 100755
--- a/ci.sh
+++ b/ci.sh
@@ -41,8 +41,8 @@ BLACK_VERSION=24.1.0
 
 if [ "$CHECK_FORMATTING" = "1" ]; then
     pip install black==${BLACK_VERSION}
-    if ! black --check setup.py tests trio_asyncio; then
-        black --diff setup.py tests trio_asyncio
+    if ! black --check tests src; then
+        black --diff tests src
         cat <<EOF
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@@ -50,7 +50,7 @@ if [ "$CHECK_FORMATTING" = "1" ]; then
 Formatting problems were found (listed above). To fix them, run
 
    pip install black==${BLACK_VERSION}
-   black setup.py tests trio_asyncio
+   black tests src
 
 in your local checkout.
 
diff --git a/docs/source/conf.py b/docs/source/conf.py
index f400d4b..b2afd10 100755
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -17,22 +17,80 @@
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
 #
+from __future__ import annotations
+
+import glob
 import os
 import sys
+from pathlib import Path
+from typing import TYPE_CHECKING, cast
+
+if TYPE_CHECKING:
+    from sphinx.application import Sphinx
+    from sphinx.util.typing import Inventory
+
 # So autodoc can import our package
 sys.path.insert(0, os.path.abspath('../..'))
 
-# https://docs.readthedocs.io/en/stable/builds.html#build-environment
-if "READTHEDOCS" in os.environ:
-    import glob
-    if glob.glob("../../newsfragments/*.*.rst"):
-        print("-- Found newsfragments; running towncrier --", flush=True)
-        import subprocess
+# Enable reloading with `typing.TYPE_CHECKING` being True
+os.environ["SPHINX_AUTODOC_RELOAD_MODULES"] = "1"
+
+# Handle writing newsfragments into the history file.
+# We want to keep files unchanged when testing locally.
+# So immediately revert the contents after running towncrier,
+# then substitute when Sphinx wants to read it in.
+history_file = Path("history.rst")
+
+history_new: str | None
+if glob.glob("../../newsfragments/*.*.rst"):
+    print("-- Found newsfragments; running towncrier --", flush=True)
+    history_orig = history_file.read_bytes()
+    import subprocess
+
+    # In case changes were staged, preserve indexed version.
+    # This grabs the hash of the current staged version.
+    history_staged = subprocess.run(
+        ["git", "rev-parse", "--verify", ":docs/source/history.rst"],
+        check=True,
+        cwd="../..",
+        stdout=subprocess.PIPE,
+        encoding="ascii",
+    ).stdout.strip()
+    try:
         subprocess.run(
-            ["towncrier", "--yes", "--date", "not released yet"],
+            ["towncrier", "--keep", "--date", "not released yet"],
             cwd="../..",
             check=True,
         )
+        history_new = history_file.read_text("utf8")
+    finally:
+        # Make sure this reverts even if a failure occurred.
+        # Restore whatever was staged.
+        print(f"Restoring history.rst = {history_staged}")
+        subprocess.run(
+            [
+                "git",
+                "update-index",
+                "--cacheinfo",
+                f"100644,{history_staged},docs/source/history.rst",
+            ],
+            cwd="../..",
+            check=False,
+        )
+        # And restore the working copy.
+        history_file.write_bytes(history_orig)
+    del history_orig  # We don't need this any more.
+else:
+    # Leave it as is.
+    history_new = None
+
+
+def on_read_source(app: Sphinx, docname: str, content: list[str]) -> None:
+    """Substitute the modified history file."""
+    if docname == "history" and history_new is not None:
+        # This is a 1-item list with the file contents.
+        content[0] = history_new
+
 
 # Warn about all references to unknown targets
 nitpicky = True
@@ -94,8 +152,9 @@
 # built documents.
 #
 # The short X.Y version.
-import trio_asyncio
-version = trio_asyncio.__version__
+import importlib.metadata
+
+version = importlib.metadata.version("trio_asyncio")
 # The full version, including alpha/beta/rc tags.
 release = version
 
diff --git a/pyproject.toml b/pyproject.toml
index cac350a..9e0e9de 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,3 +1,73 @@
+[build-system]
+# setuptools v77 adds PEP 639 support
+requires = ["setuptools >= 77"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "trio_asyncio"
+description = "A re-implementation of the asyncio mainloop on top of Trio"
+authors = [{name = "Matthias Urlichs", email = "matthias@urlichs.de"}]
+license = "MIT OR Apache-2.0"
+license-files = ["LICENSE*"]
+keywords = [
+    "async",
+    "io",
+    "trio",
+    "asyncio",
+    "trio-asyncio"
+]
+classifiers = [
+    "Development Status :: 4 - Beta",
+    "Intended Audience :: Developers",
+    "Operating System :: POSIX :: Linux",
+    "Operating System :: MacOS :: MacOS X",
+    "Operating System :: POSIX :: BSD",
+    "Operating System :: Microsoft :: Windows",
+    "Programming Language :: Python :: Implementation :: CPython",
+    "Programming Language :: Python :: Implementation :: PyPy",
+    "Programming Language :: Python :: 3 :: Only",
+    "Programming Language :: Python :: 3.9",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
+    "Topic :: System :: Networking",
+    "Framework :: Trio",
+    "Framework :: AsyncIO",
+]
+requires-python = ">=3.9"
+dependencies = [
+    "trio >= 0.22.0",
+    "outcome",
+    "sniffio >= 1.3.0",
+    "exceptiongroup >= 1.0.0; python_version < '3.11'",
+    "greenlet",
+]
+dynamic = ["version"]
+
+[project.readme]
+file = "README.rst"
+content-type = "text/x-rst"
+
+[project.urls]
+Homepage = "https://github.com/python-trio/trio-asyncio"
+Documentation = "http://trio-asyncio.readthedocs.io"
+Changelog = "https://trio-asyncio.readthedocs.io/en/latest/history.html"
+
+[tool.setuptools]
+# This means, just install *everything* you see under trio/, even if it
+# doesn't look like a source file, so long as it appears in MANIFEST.in:
+include-package-data = true
+
+[tool.setuptools.dynamic]
+version = {attr = "trio_asyncio._version.__version__"}
+
+[project.optional-dependencies]
+tests = [
+    "pytest>=5.4",
+    "pytest-trio >= 0.6",
+]
+
 [tool.pytest.ini_options]
 addopts = ["-p", "no:asyncio"]
 filterwarnings = [
diff --git a/setup.py b/setup.py
deleted file mode 100644
index 1d2a44e..0000000
--- a/setup.py
+++ /dev/null
@@ -1,100 +0,0 @@
-from setuptools import setup
-import sys
-
-exec(open("trio_asyncio/_version.py", encoding="utf-8").read())
-
-LONG_DESC = """\
-``trio-asyncio`` is a re-implementation of the ``asyncio`` mainloop on top of
-Trio.
-
-Rationale
-=========
-
-There are quite a few asyncio-compatible libraries.
-
-On the other hand, Trio has native concepts of tasks and task cancellation.
-Asyncio, on the other hand, is based on chaining Future objects, albeit
-with nicer syntax.
-
-Thus, being able to use asyncio libraries from Trio is useful.
-
-Principle of operation
-======================
-
-The core of the "normal" asyncio main loop is the repeated execution of
-synchronous code that's submitted to ``call_soon`` or
-``add_reader``/``add_writer``.
-
-Everything else within ``asyncio``, i.e. Futures and ``async``/``await``,
-is just syntactic sugar. There is no concept of a task; while a Future can
-be cancelled, that in itself doesn't affect the code responsible for
-fulfilling it.
-
-On the other hand, trio has genuine tasks with no separation between
-returning a value asynchronously, and the code responsible for providing
-that value.
-
-``trio_asyncio`` implements a task which runs (its own version of) the
-asyncio main loop. It also contains shim code which translates between these
-concepts as transparently and correctly as possible, and it supplants a few
-of the standard loop's key functions.
-
-This works rather well: ``trio_asyncio`` consists of just ~700 lines of
-code (asyncio: ~8000) but passes the complete Python 3.6 test suite with no
-errors.
-
-``trio_asyncio`` requires Python 3.9 or later.
-
-Author
-======
-
-Matthias Urlichs <matthias@urlichs.de>
-
-"""
-
-setup(
-    name="trio_asyncio",
-    version=__version__,  # noqa: F821
-    description="A re-implementation of the asyncio mainloop on top of Trio",
-    long_description=LONG_DESC,
-    author="Matthias Urlichs",
-    author_email="matthias@urlichs.de",
-    url="https://github.com/python-trio/trio-asyncio",
-    license="MIT -or- Apache License 2.0",
-    packages=["trio_asyncio"],
-    install_requires=[
-        "trio >= 0.22.0",
-        "outcome",
-        "sniffio >= 1.3.0",
-        "exceptiongroup >= 1.0.0; python_version < '3.11'",
-        "greenlet",
-    ],
-    # This means, just install *everything* you see under trio/, even if it
-    # doesn't look like a source file, so long as it appears in MANIFEST.in:
-    include_package_data=True,
-    python_requires=">=3.9",
-    keywords=["async", "io", "trio", "asyncio", "trio-asyncio"],
-    setup_requires=["pytest-runner"],
-    tests_require=["pytest >= 5.4", "pytest-trio >= 0.6", "outcome"],
-    classifiers=[
-        "Development Status :: 4 - Beta",
-        "Intended Audience :: Developers",
-        "License :: OSI Approved :: MIT License",
-        "License :: OSI Approved :: Apache Software License",
-        "Operating System :: POSIX :: Linux",
-        "Operating System :: MacOS :: MacOS X",
-        "Operating System :: POSIX :: BSD",
-        "Operating System :: Microsoft :: Windows",
-        "Programming Language :: Python :: Implementation :: CPython",
-        "Programming Language :: Python :: Implementation :: PyPy",
-        "Programming Language :: Python :: 3 :: Only",
-        "Programming Language :: Python :: 3.9",
-        "Programming Language :: Python :: 3.10",
-        "Programming Language :: Python :: 3.11",
-        "Programming Language :: Python :: 3.12",
-        "Programming Language :: Python :: 3.13",
-        "Topic :: System :: Networking",
-        "Framework :: Trio",
-        "Framework :: AsyncIO",
-    ],
-)
diff --git a/trio_asyncio/__init__.py b/src/trio_asyncio/__init__.py
similarity index 100%
rename from trio_asyncio/__init__.py
rename to src/trio_asyncio/__init__.py
diff --git a/trio_asyncio/_adapter.py b/src/trio_asyncio/_adapter.py
similarity index 100%
rename from trio_asyncio/_adapter.py
rename to src/trio_asyncio/_adapter.py
diff --git a/trio_asyncio/_async.py b/src/trio_asyncio/_async.py
similarity index 100%
rename from trio_asyncio/_async.py
rename to src/trio_asyncio/_async.py
diff --git a/trio_asyncio/_base.py b/src/trio_asyncio/_base.py
similarity index 99%
rename from trio_asyncio/_base.py
rename to src/trio_asyncio/_base.py
index 1bd4ddb..f151081 100644
--- a/trio_asyncio/_base.py
+++ b/src/trio_asyncio/_base.py
@@ -432,7 +432,7 @@ async def _make_subprocess_transport(
             stderr,
             bufsize,
             extra=None,
-            **kwargs
+            **kwargs,
         ):
             """Make a subprocess transport. Asyncio context."""
 
@@ -448,7 +448,7 @@ async def _make_subprocess_transport(
                 bufsize,
                 waiter=waiter,
                 extra=extra,
-                **kwargs
+                **kwargs,
             )
 
             async def child_wait(transp):
diff --git a/trio_asyncio/_child.py b/src/trio_asyncio/_child.py
similarity index 100%
rename from trio_asyncio/_child.py
rename to src/trio_asyncio/_child.py
diff --git a/trio_asyncio/_deprecate.py b/src/trio_asyncio/_deprecate.py
similarity index 100%
rename from trio_asyncio/_deprecate.py
rename to src/trio_asyncio/_deprecate.py
diff --git a/trio_asyncio/_handles.py b/src/trio_asyncio/_handles.py
similarity index 100%
rename from trio_asyncio/_handles.py
rename to src/trio_asyncio/_handles.py
diff --git a/trio_asyncio/_loop.py b/src/trio_asyncio/_loop.py
similarity index 100%
rename from trio_asyncio/_loop.py
rename to src/trio_asyncio/_loop.py
diff --git a/trio_asyncio/_sync.py b/src/trio_asyncio/_sync.py
similarity index 100%
rename from trio_asyncio/_sync.py
rename to src/trio_asyncio/_sync.py
diff --git a/trio_asyncio/_util.py b/src/trio_asyncio/_util.py
similarity index 100%
rename from trio_asyncio/_util.py
rename to src/trio_asyncio/_util.py
diff --git a/trio_asyncio/_version.py b/src/trio_asyncio/_version.py
similarity index 100%
rename from trio_asyncio/_version.py
rename to src/trio_asyncio/_version.py
diff --git a/tests/test_trio_asyncio.py b/tests/test_trio_asyncio.py
index dfbb7e5..4c8acdf 100644
--- a/tests/test_trio_asyncio.py
+++ b/tests/test_trio_asyncio.py
@@ -249,7 +249,10 @@ async def iterate_one(label, extra=""):
         with trio.move_on_after(loop_timeout) as scope:
             if loop_timeout == 0:
                 scope.cancel()
-            async with trio_asyncio.open_loop() as loop, trio_asyncio.open_loop() as loop2:
+            async with (
+                trio_asyncio.open_loop() as loop,
+                trio_asyncio.open_loop() as loop2,
+            ):
                 assert sys.get_asyncgen_hooks() != before_hooks
                 async with trio.open_nursery() as nursery:
                     # Make sure the iterate_one aio tasks don't get