diff --git a/.github/workflows/checks.yml b/.github/workflows/checks.yml
index a9a66d2a0a..0719ec8b42 100644
--- a/.github/workflows/checks.yml
+++ b/.github/workflows/checks.yml
@@ -18,15 +18,15 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v6
 
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@v2
+      uses: github/codeql-action/init@v4
       with:
         languages: python
 
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v2
+      uses: github/codeql-action/analyze@v4
 
   tests-linux:
     name: Unit Tests (Linux)
@@ -34,14 +34,14 @@ jobs:
 
     strategy:
       matrix:
-        python-version: ['3.8', '3.9', '3.10']
+        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v6
 
     - name: Setup Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v2.3.1
+      uses: actions/setup-python@v6.2.0
       with:
         python-version: ${{ matrix.python-version }}
 
@@ -50,7 +50,7 @@ jobs:
         echo "Installing pip + wheel..."
         python -m pip install --upgrade pip wheel
         echo "Installing python dependencies..."
-        python -m pip install -r requirements.txt
+        python -m pip install .
 
     - name: Test
       env:
@@ -63,14 +63,14 @@ jobs:
 
     strategy:
       matrix:
-        python-version: ['3.8', '3.9', '3.10']
+        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v6
 
     - name: Setup Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v2.3.1
+      uses: actions/setup-python@v6.2.0
       with:
         python-version: ${{ matrix.python-version }}
 
@@ -80,7 +80,7 @@ jobs:
         echo "Installing pip + wheel..."
         python -m pip install --upgrade pip wheel
         echo "Installing dependencies..."
-        python -m pip install -r requirements.txt
+        python -m pip install .
 
     - name: Test
       env:
diff --git a/Makefile b/Makefile
index 05808f2f99..6af1e7bac6 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,8 @@
 
 version := $(shell python id2xml/run.py --version | awk '{print $$2}' )
 
+pyversion := $(shell python -c "import sys; print(str(sys.version_info.major) + str(sys.version_info.minor))" )
+
 testfiles= \
 	draft-baba-iot-problems-03.txt				\
 	draft-ietf-6man-rfc2460bis-11.txt			\
@@ -32,7 +34,7 @@ diffiles = $(addsuffix .diff, $(basename $(resfiles)))
 tests    = $(addsuffix .test, $(basename $(resfiles)))
 pyfiles  = $(wildcard  id2xml/*.py)
 
-all: install upload
+all: install upload man
 
 %.1: id2xml/run.py id2xml/__init__.py Makefile
 	id2xml -h | sed -e 's/^  -/\n  -/'			\
@@ -40,18 +42,15 @@ all: install upload
 		  | txt2man -s1 -r'RFC Format Tools' -t $< > $@
 
 
-%.1.gz:	%.1
+man: %.1
 	gzip < $< > $@
 
 pyflakes:
 	pyflakes id2xml
 
 	
-install: id2xml/id2xml.1.gz
-	python setup.py -q install
-
-env/bin/id2xml:	$(pyfiles) setup.py
-	python setup.py -q install
+install: $(pyfiles) pyproject.toml
+	python -m pip install .[test]
 
 
 # ------------------------------------------------------------------------
@@ -62,7 +61,7 @@ env/bin/id2xml:	$(pyfiles) setup.py
 # ------------------------------------------------------------------------
 # test
 
-test:	env/bin/id2xml clean $(resfiles) $(xml3files) $(diffiles) $(tests) 
+test:	id2xml clean $(resfiles) $(xml3files) $(diffiles) $(tests) 
 
 .PHONY: clean
 clean:
@@ -114,17 +113,17 @@ test/out/%.v3.xml:	test/in/%.txt $(pyfiles)
 
 # ------------------------------------------------------------------------
 
-dist/id2xml-$(version).tar.gz: MANIFEST.in setup.py $(pyfiles)
-	python setup.py -q sdist
+dist/id2xml-$(version).tar.gz: MANIFEST.in pyproject.toml $(pyfiles)
+	python -m build --sdist
 
-dist/id2xml-$(version)-py27-none-any.whl: MANIFEST.in setup.py $(pyfiles)
-	python setup.py -q bdist_wheel --python-tag py27
+dist/id2xml-$(version)-py$(pyversion)-none-any.whl: MANIFEST.in pyproject.toml $(pyfiles)
+	python -m build --wheel
 
 dist/%.asc: dist/%
 	gpg --detach-sign -a $<
 
 sdist:		dist/id2xml-$(version).tar.gz			dist/id2xml-$(version).tar.gz.asc
-bdist_wheel:	dist/id2xml-$(version)-py27-none-any.whl	dist/id2xml-$(version)-py27-none-any.whl.asc
+bdist_wheel:	dist/id2xml-$(version)-py$(pyversion)-none-any.whl	dist/id2xml-$(version)-py$(pyversion)-none-any.whl.asc
 
 dist:	test sdist # bdist_wheel
 
diff --git a/bin/mkrelease b/bin/mkrelease
index b89c04413d..010c157d88 100755
--- a/bin/mkrelease
+++ b/bin/mkrelease
@@ -181,7 +181,7 @@ changes=$( sed -n "/^$PROJ ($VER)/,/^ -- /p" changelog )
 note "$changes"
 
 note "Upgrading the python library modules before checking migrations and running tests ..."
-$do pip install --upgrade -r requirements.txt
+$do pip install --upgrade .
 
 note "Running the tests suite ..."
 $do make test
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000000..385b8008ba
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,66 @@
+# -------------------------------------------------------
+# Copyright The IETF Trust 2011-2026, All Rights Reserved
+# -------------------------------------------------------
+[build-system]
+requires = ["setuptools", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "id2xml"
+version = "1.5.2"
+authors = [
+  {name = "Henrik Levkowetz", email = "henrik@levkowetz.com"},
+]
+
+description = "Convert text-format RFCs and Internet-Drafts to .xml format"
+keywords = ["ietf", "rfc", "text", "internet-draft", "xml"]
+readme = "README.rst"
+license = "BSD-3-Clause"
+license-files = ["LICENSE"]
+requires-python = ">=3.9"
+classifiers = [
+    'Intended Audience :: Other Audience',
+    'Topic :: Text Processing',
+    'Topic :: Text Processing :: Markup :: XML',
+    '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',
+    'Programming Language :: Python :: 3.14',
+]
+
+dependencies = [
+    "lxml",
+    "pathlib2",
+    "six",
+    "xml2rfc>=2.8.2",
+    "decorator",
+]
+
+[project.urls]
+homepage = "https://github.com/ietf-tools/id2xml"
+source = "https://github.com/ietf-tools/id2xml"
+issues = "https://github.com/ietf-tools/id2xml/issues"
+releasenotes = "https://github.com/ietf-tools/id2xml/releases"
+
+[project.optional-dependencies]
+test = [
+        "coverage",
+        "pycodestyle",
+        "pyflakes",
+        "tox",
+]
+dev = [
+        "twine",
+]
+
+[project.scripts]
+id2xml = "id2xml.run:run"
+
+[tool.setuptools]
+packages = ["id2xml"]
+include-package-data = true
+
+[tool.setuptools.package-data]
+id2xml = ["data/*", "debug.py", "utils.py", "run.py"]
diff --git a/requirements.txt b/requirements.txt
deleted file mode 100644
index 34223a3179..0000000000
--- a/requirements.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-lxml
-pathlib2
-six
-xml2rfc>=2.8.2
-decorator
diff --git a/setup.py b/setup.py
deleted file mode 100644
index bf3801aeee..0000000000
--- a/setup.py
+++ /dev/null
@@ -1,167 +0,0 @@
-#!/usr/bin/env python
-# --------------------------------------------------
-# Copyright The IETF Trust 2011, All Rights Reserved
-# --------------------------------------------------
-
-import re
-
-from setuptools import setup, find_packages
-from codecs import open
-from os import path
-
-
-here = path.abspath(path.dirname(__file__))
-
-# Get the long description from the README file
-with open(path.join(here, 'README.rst'), encoding='utf-8') as file:
-    long_description = file.read()
-
-# Get the requirements from the local requirements.txt file
-with open(path.join(here, 'requirements.txt'), encoding='utf-8') as file:
-    requirements = file.read().splitlines()
-
-# Get the requirements from the local requirements.txt file
-with open(path.join(here, 'MANIFEST.in'), encoding='utf-8') as file:
-    extra_files = [ l.split()[1] for l in file.read().splitlines() if l ]
-
-def parse(changelog):
-    ver_line = "^([a-z0-9+-]+) \(([^)]+)\)(.*?) *$"
-    sig_line = "^ -- ([^<]+) <([^>]+)>  (.*?) *$"
-    #
-    entries = []
-    if type(changelog) == type(''):
-        changelog = open(changelog)
-    for line in changelog:
-        if re.match(ver_line, line):
-            package, version, rest = re.match(ver_line, line).groups()
-            entry = {}
-            entry["package"] = package
-            entry["version"] = version
-            entry["logentry"] = ""
-        elif re.match(sig_line, line):
-            author, email, date = re.match(sig_line, line).groups()
-            entry["author"] = author
-            entry["email"] = email
-            entry["datetime"] = date
-            entry["date"] = " ".join(date.split()[:3])
-            entries += [ entry ]
-        else:
-            entry["logentry"] += line
-    changelog.close()
-    entry["logentry"] = entry["logentry"].strip()
-    return entries
-
-changelog_entry_template = """
-Version %(version)s (%(date)s)
-------------------------------------------------
-
-%(logentry)s"""
-
-long_description += """
-Changelog
-=========
-""" + "\n".join([ changelog_entry_template % entry for entry in parse("changelog")[:2] ])
-
-
-
-import id2xml
-
-setup(
-    name='id2xml',
-
-    # Versions should comply with PEP440.  For a discussion on single-sourcing
-    # the version across setup.py and the project code, see
-    # https://packaging.python.org/en/latest/single_source_version.html
-    version=id2xml.__version__,
-
-    description="Convert text-format RFCs and Internet-Drafts to .xml format",
-    long_description=long_description,
-
-    # The project's main homepage.
-    url='https://tools.ietf.org/tools/ietfdb/browser/branch/elft/id2xml/',
-
-    # Author details
-    author='Henrik Levkowetz',
-    author_email='henrik@levkowetz.com',
-
-    # Choose your license
-    license='Simplified BSD',
-
-    # See https://pypi.python.org/pypi?%3Aaction=list_classifiers
-    classifiers=[
-        # How mature is this project? Common values are
-        #   3 - Alpha
-        #   4 - Beta
-        #   5 - Production/Stable
-        'Development Status :: 5 - Production/Stable',
-
-        # Indicate who your project is intended for
-        'Intended Audience :: Other Audience',
-        'Topic :: Text Processing',
-        'Topic :: Text Processing :: Markup :: XML',
-
-        # Pick your license as you wish (should match "license" above)
-        'License :: OSI Approved :: BSD License',
-
-        # Specify the Python versions you support here. In particular, ensure
-        # that you indicate whether you support Python 2, Python 3 or both.
-        'Programming Language :: Python :: 2.7',
-        #'Programming Language :: Python :: 3',
-        #'Programming Language :: Python :: 3.3',
-        #'Programming Language :: Python :: 3.4',
-        'Programming Language :: Python :: 3.5',
-        'Programming Language :: Python :: 3.6',
-        'Programming Language :: Python :: 3.7',
-    ],
-
-    # What does your project relate to?
-    keywords='Internet-Draft text to xml conversion',
-
-    # You can just specify the packages manually here if your project is
-    # simple. Or you can use find_packages().
-    packages=find_packages(exclude=['contrib', 'docs', 'tests']),
-
-    # Alternatively, if you want to distribute just a my_module.py, uncomment
-    # this:
-    #py_modules=["debug"],
-
-    # List run-time dependencies here.  These will be installed by pip when
-    # your project is installed. For an analysis of "install_requires" vs pip's
-    # requirements files see:
-    # https://packaging.python.org/en/latest/requirements.html
-    install_requires=requirements,
-
-    # List additional groups of dependencies here (e.g. development
-    # dependencies). You can install these using the following syntax,
-    # for example:
-    # $ pip install -e .[dev,test]
-    extras_require={
-        'dev': ['twine',],
-        #'test': ['coverage'],
-    },
-
-    # If there are data files included in your packages that need to be
-    # installed, specify them here.  If using Python 2.6 or less, then these
-    # have to be included in MANIFEST.in as well.
-    package_data={
-        'id2xml': ['data/*', 'id2xml.1.gz', 'debug.py', 'utils.py', 'run.py' ],
-    },
-
-    # Although 'package_data' is the preferred approach, in some case you may
-    # need to place data files outside of your packages. See:
-    # http://docs.python.org/3.4/distutils/setupscript.html#installing-additional-files # noqa
-    # In this case, 'data_file' will be installed into '<sys.prefix>/my_data'
-    # data_files=[('/usr/local/share/man/man1', ['id2xml/id2xml.1.gz',])],
-
-    # To provide executable scripts, use entry points in preference to the
-    # "scripts" keyword. Entry points provide cross-platform support and allow
-    # pip to create the appropriate form of executable for the target platform.
-    entry_points={
-        'console_scripts': [
-            'id2xml=id2xml.run:run',
-        ],
-    },
-
-    # We're reading schema files from a package directory.
-    zip_safe = False,                   
-)