diff --git a/README.rst b/README.rst
index 22960ef..17029b0 100644
--- a/README.rst
+++ b/README.rst
@@ -175,6 +175,7 @@ Version History
 ======= ============ ===========================================================
 Version Release date Changes
 ------- ------------ -----------------------------------------------------------
+v0.3.4  2022-11-17   - Replaces ``setup.py`` with ``pyproject.toml`` for build.
 v0.3.3  2022-05-16   - Cope with line-length as string in pyproject.toml config.
 v0.3.2  2022-02-25   - Use ``tomli`` library to match black, contribution from
                        `Brian Helba <https://github.com/brianhelba>`_.
@@ -223,10 +224,15 @@ Developers
 
 This plugin is on GitHub at https://github.com/peterjc/flake8-black
 
+Developers may install the plugin from the git repository with optional build
+dependencies::
+
+    $ pip install -e .[develop]
+
 To make a new release once tested locally and online::
 
     $ git tag vX.Y.Z
-    $ python setup.py sdist --formats=gztar && python setup.py bdist_wheel
+    $ python -m build
     $ git push origin master --tags
     $ twine upload dist/flake8?black-X.Y.Z*
 
diff --git a/flake8_black.py b/flake8_black.py
index aaf762c..8d0b1d2 100644
--- a/flake8_black.py
+++ b/flake8_black.py
@@ -14,7 +14,7 @@
 from flake8 import LOG
 
 
-__version__ = "0.3.3"
+__version__ = "0.3.4"
 
 black_prefix = "BLK"
 
@@ -223,7 +223,7 @@ def run(self):
             except BadBlackConfig as err:
                 msg = "997 Invalid TOML file: %s" % err
             except Exception as err:
-                msg = "999 Unexpected exception: %s" % err
+                msg = "999 Unexpected exception: %r" % err
             else:
                 assert (
                     new_code != source
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..ca698cb
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,49 @@
+[build-system]
+requires = ['pip>=21.3', 'setuptools>=61', 'wheel']
+build-backend = 'setuptools.build_meta'
+
+[project]
+name = 'flake8-black'
+description = 'flake8 plugin to call black as a code style validator'
+keywords = ['black', 'formatting', 'style', 'flake8']
+license = {text = 'MIT'}
+readme = 'README.rst'
+authors = [
+  {name = 'Peter J. A. Cock'}
+]
+maintainers = [
+  {name = 'Peter J. A. Cock', email = 'p.j.a.cock@googlemail.com'}
+]
+classifiers = [
+  'Intended Audience :: Developers',
+  'Framework :: Flake8',
+  'License :: OSI Approved :: MIT License',
+  'Operating System :: OS Independent',
+  'Topic :: Software Development :: Libraries :: Python Modules',
+  'Topic :: Software Development :: Quality Assurance',
+  'Programming Language :: Python',
+  'Programming Language :: Python :: 3',
+  'Programming Language :: Python :: 3 :: Only'
+]
+requires-python = '>=3.7'
+dependencies = [
+  'flake8>=3',
+  'black>=22.1.0',
+  'tomli',
+]
+dynamic = ['version']
+[project.entry-points]
+'flake8.extension' = {RST = 'flake8_black:BlackStyleChecker'}
+[project.optional-dependencies]
+develop = ['build', 'twine']
+[project.urls]
+Homepage = 'https://github.com/peterjc/flake8-black'
+'Source Code' = 'https://github.com/peterjc/flake8-black/'
+'Bug Tracker' = 'https://github.com/peterjc/flake8-black/issues'
+Documentation = 'https://github.com/peterjc/flake8-black/blob/master/README.rst'
+
+[tool.setuptools]
+py-modules = ['flake8_black']
+zip-safe = true
+[tool.setuptools.dynamic]
+version = {attr = 'flake8_black.__version__'}
diff --git a/setup.py b/setup.py
deleted file mode 100644
index cf38ed2..0000000
--- a/setup.py
+++ /dev/null
@@ -1,47 +0,0 @@
-"""Setup file for building/installing flake8-black."""
-
-from __future__ import with_statement
-
-from setuptools import setup
-
-
-def get_version(fname="flake8_black.py"):
-    """Parse our source code to get the current version number."""
-    with open(fname) as f:
-        for line in f:
-            if line.startswith("__version__"):
-                return eval(line.split("=")[-1])
-
-
-setup(
-    name="flake8-black",
-    version=get_version(),
-    description="flake8 plugin to call black as a code style validator",
-    long_description=open("README.rst").read(),
-    license="MIT",
-    author="Peter J. A. Cock",
-    author_email="p.j.a.cock@googlemail.com",
-    url="https://github.com/peterjc/flake8-black",
-    project_urls={
-        "Documentation": (
-            "https://github.com/peterjc/flake8-black/blob/master/README.rst"
-        ),
-        "Source": "https://github.com/peterjc/flake8-black/",
-        "Tracker": "https://github.com/peterjc/flake8-black/issues",
-    },
-    classifiers=[
-        "Intended Audience :: Developers",
-        "Framework :: Flake8",
-        "Programming Language :: Python",
-        "Programming Language :: Python :: 3",
-        "Operating System :: OS Independent",
-        "License :: OSI Approved :: MIT License",
-        "Topic :: Software Development :: Libraries :: Python Modules",
-        "Topic :: Software Development :: Quality Assurance",
-    ],
-    keywords="PEP8",
-    py_modules=["flake8_black"],
-    python_requires=">=3.7",
-    install_requires=["flake8 >= 3.0.0", "black >= 22.1.0", "tomli"],
-    entry_points={"flake8.extension": ["BLK = flake8_black:BlackStyleChecker"]},
-)