diff --git a/.gitignore b/.gitignore
index 0dccebb..e456c8f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,9 +2,10 @@ build
 dist
 *.egg*
 *.py[co]
+.tox
+.coverage
 docs/_*
 datetime_tz/win32tz_map.py
-py2
-py3
+release_venv
 venv
 venv3
diff --git a/.travis.yml b/.travis.yml
index b1c557a..5f83dcd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,15 +1,17 @@
 language: python
 python:
-  - 2.6
   - 2.7
-  - 3.3
-  - 3.4
+  - 3.6
+  - 3.7
+  - 3.8
   - nightly
+dist: xenial
 
 matrix:
  allow_failures:
    - python: nightly
 
+
 sudo: false
 
 cache:
@@ -19,15 +21,12 @@ cache:
 
 install:
   - pip install --upgrade pip
-  - pip install pyopenssl ndg-httpsclient pyasn1
-  - pip install -r requirements.txt
-  - python setup.py install
-  - python run_tests_all_pytz.py --download-only
+  - pip install --upgrade tox
 
 script:
-  - python run_tests_all_pytz.py
+  - ./test_multiple_pytz_versions.sh
+  - tox -e py
 
 after_success:
   - pip install coveralls
-  - coverage run --source=datetime_tz setup.py test
-  - coveralls
+  - coveralls  # Coverage generated by tox run
diff --git a/README.md b/README.md
index 6fd46ad..58b1132 100644
--- a/README.md
+++ b/README.md
@@ -19,9 +19,9 @@ This module depends on:
 
 For development:
  * PyLint - Needed for checking for link.
- * Genshi - Needed for building windows mapping file.
+ * defusedxml - Needed for building windows mapping file.
 
 [![Build Status](https://travis-ci.org/mithro/python-datetime-tz.png?branch=master)](https://travis-ci.org/mithro/python-datetime-tz)
 [![Coverage Status](https://coveralls.io/repos/mithro/python-datetime-tz/badge.png)](https://coveralls.io/r/mithro/python-datetime-tz)
-[![PyPi Version](https://pypip.in/v/python-datetime-tz/badge.png)](https://crate.io/packages/python-coveralls/)
-[![PyPi Downloads](https://pypip.in/d/python-datetime-tz/badge.png)](https://crate.io/packages/python-coveralls/)
+[![PyPi Version](https://img.shields.io/pypi/v/python-datetime-tz.svg)](https://pypi.org/project/python-datetime-tz/)
+[![PyPi Downloads](https://img.shields.io/pypi/dm/python-datetime-tz.svg)](https://pypi.org/project/python-datetime-tz/)
diff --git a/datetime_tz/__init__.py b/datetime_tz/__init__.py
index a4387ce..e939a56 100644
--- a/datetime_tz/__init__.py
+++ b/datetime_tz/__init__.py
@@ -217,7 +217,7 @@ def detect_timezone():
   if tz is not None:
     return tz
 
-  # Next we try and use a similiar method to what PHP does.
+  # Next we try and use a similar method to what PHP does.
   # We first try to search on time.tzname, time.timezone, time.daylight to
   # match a pytz zone.
   warnings.warn("Had to fall back to worst detection method (the 'PHP' "
@@ -691,7 +691,7 @@ def smartparse(cls, toparse, tzinfo=None):
         if isinstance(dt.tzinfo, pytz_abbr.tzabbr):
           abbr = dt.tzinfo
           dt = dt.replace(tzinfo=None)
-          dt = cls(dt, abbr.zone, is_dst=abbr.dst)
+          dt = cls(dt, abbr.zone, is_dst=abbr.is_dst)
 
         dt = cls(dt)
 
@@ -866,7 +866,7 @@ def _wrap_method(name):
   # Have to give the second argument as method has no __module__ option.
   @functools.wraps(method, ("__name__", "__doc__"), ())
   def wrapper(self, *args, **kw):
-    r = method(self, *args, **kw)
+    r = method(self.asdatetime(naive=False), *args, **kw)
 
     if isinstance(r, datetime.datetime) and not isinstance(r, type(self)):
       r = type(self)(r)
diff --git a/datetime_tz/detect_windows.py b/datetime_tz/detect_windows.py
index 3f708aa..b2fe6db 100644
--- a/datetime_tz/detect_windows.py
+++ b/datetime_tz/detect_windows.py
@@ -116,7 +116,12 @@ def _detect_timezone_windows():
           win32timezone.TimeZoneInfo._get_indexed_time_zone_keys("Std"))
     win32tz_key_name = win32timezone_to_en.get(win32tz_name, win32tz_name)
 
-  territory = locale.getdefaultlocale()[0].split("_", 1)[1]
+  language_code = locale.getdefaultlocale()[0]
+  if language_code is None:
+    # Failure getting the system locale, result may be wrong!
+    territory = None
+  else:
+    territory = language_code.split("_", 1)[1]
   olson_name = win32tz_map.win32timezones.get((win32tz_key_name, territory), win32tz_map.win32timezones.get(win32tz_key_name, None))
   if not olson_name:
     return None
diff --git a/datetime_tz/pytz_abbr.py b/datetime_tz/pytz_abbr.py
index c97e460..3470324 100644
--- a/datetime_tz/pytz_abbr.py
+++ b/datetime_tz/pytz_abbr.py
@@ -47,19 +47,63 @@
 import pytz
 import pytz.tzfile
 
+try:
+  basestring
+except NameError:
+  # pylint: disable=redefined-builtin
+  basestring = str
+
 
 class tzabbr(datetime.tzinfo):
   """A timezone abbreviation.
 
-  *WARNING*: This is not a tzinfo implementation! Trying to use this as tzinfo
-  object will result in failure.  We inherit from datetime.tzinfo so we can get
-  through the dateutil checks.
+  *WARNING*: This is a proxy object for an underlying `pytz` object only
+  intended to allow dateutil to probe the localized datetime for information.
+  datetime_tz's parsing logic will replace it with the relevant pytz zone
+  before returning to the end user.
   """
-  pass
+
+  def __init__(self, abbr, name, region, zone, dst):
+    super(tzabbr, self).__init__()
+
+    self.abbr = abbr
+    self.name = name
+    self.region = region
+
+    if isinstance(zone, basestring):
+      zone = pytz.timezone(zone)
+
+    self.zone = zone
+    self.is_dst = dst
+
+  def _get_localized(self, dt):
+    # To make this a fully-functioning pass-through to the underlying pytz
+    # zone, we would want to use `fold` to set `is_dst`, but since this is
+    # only a temporary proxy for the zone, we will fix the DST status
+    return self.zone.localize(dt.replace(tzinfo=None), is_dst=self.is_dst)
+
+  def tzname(self, dt):
+    return self._get_localized(dt).tzname()
+
+  def utcoffset(self, dt):
+    return self._get_localized(dt).utcoffset() # pragma: no cover
+
+  def dst(self, dt):
+    return self._get_localized(dt).dst() # pragma: no cover
 
 
 # A "marker" tzinfo object which is used to signify an unknown timezone.
-unknown = datetime.tzinfo()
+class _UnknownZone(datetime.tzinfo):
+  def tzname(self, dt):
+    return "UNK"
+
+  def dst(self, dt):
+    return None
+
+  def utcoffset(self, dt):
+    return datetime.timedelta(0)  # pragma: no cover
+
+unknown = _UnknownZone()
 
 
 regions = {"all": {}, "military": {}}
@@ -74,12 +118,7 @@ def tzabbr_register(abbr, name, region, zone, dst):
   If another abbreviation with the same name has already been registered it new
   abbreviation will only be registered in region specific dictionary.
   """
-  newabbr = tzabbr()
-  newabbr.abbr = abbr
-  newabbr.name = name
-  newabbr.region = region
-  newabbr.zone = zone
-  newabbr.dst = dst
+  newabbr = tzabbr(abbr, name, region, zone, dst)
 
   if abbr not in all:
     all[abbr] = newabbr
diff --git a/datetime_tz/update_win32tz_map.py b/datetime_tz/update_win32tz_map.py
index ad479b5..371ec62 100644
--- a/datetime_tz/update_win32tz_map.py
+++ b/datetime_tz/update_win32tz_map.py
@@ -23,15 +23,7 @@
 import hashlib
 import os
 
-try:
-  import urllib.request as urllib2
-except ImportError:
-  import urllib2
-
-try:
-  from io import StringIO
-except ImportError:
-  from StringIO import StringIO
+from defusedxml import ElementTree
 
 try:
   # pylint: disable=redefined-builtin
@@ -39,14 +31,17 @@
 except ImportError:
   pass
 
-import genshi.input
 try:
   from datetime_tz import win32tz_map
 except ImportError:
   win32tz_map = None
 
+try:
+  import urllib.request as urllib2
+except ImportError:
+  import urllib2
 
-_CLDR_WINZONES_URL = "http://www.unicode.org/repos/cldr/trunk/common/supplemental/windowsZones.xml"  # pylint: disable=line-too-long
+_CLDR_WINZONES_URL = "https://github.com/unicode-org/cldr/raw/master/common/supplemental/windowsZones.xml" # pylint: disable=line-too-long
 
 
 def download_cldr_win32tz_map_xml():
@@ -61,35 +56,27 @@ def create_win32tz_map(windows_zones_xml):
     windows_zones_xml: The CLDR XML mapping.
 
   Yields:
-    (win32_name, olson_name, comment)
+    For "default" territory (001): (win32_name, olson_name)
+    Where territory is set: ((win32_name, territory), olson_name)
   """
-  coming_comment = None
-  win32_name = None
-  territory = None
-  parser = genshi.input.XMLParser(StringIO(windows_zones_xml))
-  map_zones = {}
-  zone_comments = {}
-
-  for kind, data, _ in parser:
-    if kind == genshi.core.START and str(data[0]) == "mapZone":
-      attrs = data[1]
-      win32_name, territory, olson_name = (
-          attrs.get("other"), attrs.get("territory"), attrs.get("type").split(" ")[0])
-
-      map_zones[(win32_name, territory)] = olson_name
-    elif kind == genshi.core.END and str(data) == "mapZone" and win32_name:
-      if coming_comment:
-        zone_comments[(win32_name, territory)] = coming_comment
-        coming_comment = None
-      win32_name = None
-    elif kind == genshi.core.COMMENT:
-      coming_comment = data.strip()
-    elif kind in (genshi.core.START, genshi.core.END, genshi.core.COMMENT):
-      coming_comment = None
-
-  for win32_name, territory in sorted(map_zones):
-    yield (win32_name, territory, map_zones[(win32_name, territory)],
-           zone_comments.get((win32_name, territory), None))
+  parser = ElementTree.fromstring(windows_zones_xml)
+  map_timezones = parser.find("windowsZones").find("mapTimezones")
+
+  for child in map_timezones:
+    if child.tag == "mapZone":
+      win32_name = str(child.attrib.get("other", ""))
+      territory = str(child.attrib.get("territory", ""))
+      # Some `type` parameters are have multiple values, separated by spaces
+      # eg: "America/Denver America/Boise"
+      olson_name = str(child.attrib.get("type", "")).split(" ")[0]
+
+      if not win32_name or not olson_name:
+        continue
+
+      if territory == "001" or not territory:
+        yield (win32_name, olson_name)
+      else:
+        yield ((win32_name, territory), olson_name)
 
 
 def update_stored_win32tz_map():
@@ -97,9 +84,6 @@ def update_stored_win32tz_map():
   windows_zones_xml = download_cldr_win32tz_map_xml()
   source_hash = hashlib.md5(windows_zones_xml).hexdigest()
 
-  if hasattr(windows_zones_xml, "decode"):
-    windows_zones_xml = windows_zones_xml.decode("utf-8")
-
   map_zones = create_win32tz_map(windows_zones_xml)
   map_dir = os.path.dirname(os.path.abspath(__file__))
   map_filename = os.path.join(map_dir, "win32tz_map.py")
@@ -110,24 +94,16 @@ def update_stored_win32tz_map():
       return False
 
   map_file = open(map_filename, "w")
+  map_file.write((
+      "'''Map between Windows and Olson timezones taken from {0}\n"
+      "Generated automatically by {1}'''\n"
+      "source_hash = {2!r}  # md5 sum of xml source data\n"
+      "win32timezones = {{\n"
+    ).format(_CLDR_WINZONES_URL, __file__, source_hash))
+
+  for z in map_zones:
+    map_file.write("  %r: %r,\n" % z)
 
-  comment = "Map between Windows and Olson timezones taken from %s" % (
-      _CLDR_WINZONES_URL,)
-  comment2 = "Generated automatically from datetime_tz.py"
-  map_file.write("'''%s\n" % comment)
-  map_file.write("%s'''\n" % comment2)
-
-  map_file.write("source_hash = '%s' # md5 sum of xml source data\n" % (
-      source_hash))
-
-  map_file.write("win32timezones = {\n")
-  for win32_name, territory, olson_name, comment in map_zones:
-    if territory == '001':
-      map_file.write("  %r: %r, # %s\n" % (
-          str(win32_name), str(olson_name), comment or ""))
-    else:
-      map_file.write("  %r: %r, # %s\n" % (
-          (str(win32_name), str(territory)), str(olson_name), comment or ""))
   map_file.write("}\n")
 
   map_file.close()
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..cc8a7b5
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,9 @@
+[build-system]
+requires = [
+    "setuptools>=41.0",
+    "wheel",
+    "defusedxml",
+    "python-dateutil>=2.0",
+    "pytz >= 2011g",
+]
+build-backend = "setuptools.build_meta"
diff --git a/release.sh b/release.sh
index 29c71b7..ff0c182 100755
--- a/release.sh
+++ b/release.sh
@@ -1,33 +1,15 @@
-#!/bin/bash
-
-rm -rf py2
-virtualenv-2.7 py2
+#!/bin/bash -e
+rm -rf release_env
+rm -rf dist/
+python3 -m virtualenv release_env
+source release_env/bin/activate
 (
-  . py2/bin/activate
-  pip install --upgrade pip
-  pip install --upgrade setuptools
-  pip install -r requirements.txt
-  pip install wheel
-  python setup.py clean
-  python setup.py sdist
-  python setup.py bdist_wheel
-  python setup.py sdist upload
-  python setup.py bdist_wheel upload
-  #PS1="py2setup # " bash --norc
-)
+pip install -U pip
+pip install -U twine
+pip install -U pep517
+# Run the build
+python -m pep517.build . -b -s
 
-rm -rf py3
-virtualenv-3.4 py3
-(
-  . py3/bin/activate
-  pip install --upgrade pip
-  pip install --upgrade setuptools
-  pip install wheel
-  pip install -r requirements.txt
-  python setup.py clean
-  python setup.py sdist
-  python setup.py bdist_wheel
-  python setup.py sdist upload
-  python setup.py bdist_wheel upload
-  #PS1="py3setup # " bash --norc
+# Upload the files with twine
+twine upload dist/*
 )
diff --git a/requirements.txt b/requirements.txt
index cb8df59..63e0490 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
-Genshi
+defusedxml
 python-dateutil
-pytz>=2007g
+pytz>=2011g
diff --git a/run_tests_all_pytz.py b/run_tests_all_pytz.py
deleted file mode 100755
index 6b26ac3..0000000
--- a/run_tests_all_pytz.py
+++ /dev/null
@@ -1,148 +0,0 @@
-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
-# vim: set ts=2 sw=2 et sts=2 ai:
-#
-# Copyright 2015 Google Inc.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-
-# pylint doesn't understand the from __future__ import which must be the first
-# line of the file.
-# pylint: disable=missing-docstring,pointless-string-statement
-# pylint: disable=g-statement-before-imports
-
-from __future__ import print_function
-
-"""Run the tests against every pytz version available."""
-
-__author__ = "tansell@google.com (Tim Ansell)"
-
-import glob
-import os
-import os.path
-import subprocess
-import sys
-
-try:
-  # pylint: disable=g-import-not-at-top
-  from urllib.request import urlopen
-except ImportError:
-  # pylint: disable=g-import-not-at-top
-  from urllib import urlopen
-
-try:
-  # pylint: disable=g-import-not-at-top
-  import simplejson
-except ImportError:
-  # pylint: disable=g-import-not-at-top
-  import json as simplejson
-
-
-if not hasattr(sys, "real_prefix"):
-  print("""\
-This script should only be run inside a virtualenv because it is going to
-modify the install version of things.
-""")
-  sys.exit(1)
-
-CACHE_DIR = os.path.expanduser(os.path.join("~", ".cache", "pypi"))
-if not os.path.exists(CACHE_DIR):
-  os.makedirs(CACHE_DIR)
-print("Using a download cache directory of", repr(CACHE_DIR))
-
-# Get the pytz versions from pypi
-pypi_data_raw = urlopen(
-    "https://pypi.python.org/pypi/pytz/json").read().decode("utf-8")
-pypi_data = simplejson.loads(pypi_data_raw)
-
-
-# Hack to work around https://github.com/pypa/pip/issues/2902
-def mangle_release(rel):
-  if rel < "2007g":
-    return None
-
-  # pytz is only supported on Python 3 from version 2011b.
-  if sys.version[:3] >= "3.0" and rel < "2011g":
-    return None
-
-  if rel.endswith("r"):
-    return rel[:-1]+".post0"
-  return rel
-
-releases = pypi_data["releases"]
-# Download the pytz versions into the cache.
-for release in sorted(releases):
-  # These lines shouldn't be needed but pypi always runs setup.py even when
-  # downloading.
-  filename = "*pytz-"+release+"*"
-  if glob.glob(os.path.join(CACHE_DIR, filename)):
-    print("Not downloading release", release, "(already downloaded).")
-    continue
-
-  mangled = mangle_release(release)
-  if not mangled:
-    continue
-
-  print("Downloading pytz release", release)
-  print("="*75)
-  subprocess.check_call("""\
-pip install \
-    --pre \
-    --no-binary all \
-    --download %s \
-    pytz==%s
-""" % (CACHE_DIR, mangled), shell=True)
-  print("-"*75)
-
-if "--download-only" in sys.argv:
-  sys.exit(0)
-
-success = []
-failures = []
-for release in sorted(releases):
-  mangled = mangle_release(release)
-  if not mangled:
-    print("Skipping release", release, "as it is isn't supported")
-    continue
-
-  print()
-  print("Running tests with pytz release", release)
-  print("="*75)
-  print("Installing...")
-  subprocess.check_call("""\
-pip install \
-    --pre \
-    --no-binary all \
-    --no-index \
-    --find-links=file://%s \
-    pytz==%s
-""" % (CACHE_DIR, mangled), shell=True)
-  print("-"*75)
-  print("Running tests...")
-  t = subprocess.Popen("python setup.py test", shell=True)
-  if t.wait() != 0:
-    failures.append(release)
-  else:
-    success.append(release)
-  print("="*75)
-
-print("Tests passed on pytz versions:")
-print(success)
-print()
-print("Tests failed on pytz versions:")
-print(failures)
-print("="*75)
-
-if failures:
-  sys.exit(1)
diff --git a/setup.py b/setup.py
index 44f572d..5816dd6 100644
--- a/setup.py
+++ b/setup.py
@@ -18,13 +18,13 @@
 #
 
 import os
+import sys
+
+from setuptools import setup
+from setuptools.command import sdist, install
 
-try:
-    from setuptools import setup
-    from setuptools.command import sdist, install
-except ImportError:
-    from distutils.core import setup
-    from distutils.command import sdist, install
+# Required in order to import datetime_tz in PEP 517 builds
+sys.path.append(os.path.dirname(__file__))
 
 class update_sdist(sdist.sdist):
     def run(self):
@@ -40,11 +40,10 @@ def run(self):
             update_win32tz_map.update_stored_win32tz_map()
         install.install.run(self)
 
-import sys
 
 data = dict(
     name='python-datetime-tz',
-    version='0.5.3',
+    version='0.5.4',
     author='Tim Ansell',
     author_email='mithro@mithis.com',
     url='http://github.com/mithro/python-datetime-tz',
@@ -60,22 +59,15 @@ def run(self):
         "Topic :: Software Development :: Internationalization",
     ],
     packages=['datetime_tz'],
-    install_requires=[],
-    setup_requires=['Genshi'],
+    install_requires=[
+        "defusedxml",
+        "python-dateutil >= 2.0",
+        "pytz >= 2011g",
+    ],
     py_modules=['datetime_tz','datetime_tz.pytz_abbr'],
     test_suite='tests',
     cmdclass={'sdist': update_sdist, "install": update_install},
 )
 
-deps = []
-if sys.version[:3] < '3.0':
-    deps += ['pytz >= 2007g']
-    deps += ['python-dateutil >= 1.4']
-else:
-    deps += ['pytz >= 2011g']
-    deps += ['python-dateutil >= 2.0']
-
-data['install_requires'] += deps
-data['setup_requires'] += deps
 
 setup(**data)
diff --git a/test_multiple_pytz_versions.sh b/test_multiple_pytz_versions.sh
new file mode 100755
index 0000000..80e9c91
--- /dev/null
+++ b/test_multiple_pytz_versions.sh
@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+set -e
+
+versions=( 2011g 2014.1 2016.1 2016.6.1 2017.2 2018.3 2018.9 )
+for version in ${versions[@]}; do
+  PYTZ_VERSION="==$version" tox -e py
+done
+
+
diff --git a/tests.py b/tests.py
index 3d72682..b790bfd 100644
--- a/tests.py
+++ b/tests.py
@@ -254,30 +254,31 @@ def os_path_exists_fake(filename, os_path_exists=os.path.exists):
     self.mocked("os.path.exists", os_path_exists_fake)
 
     # Check that when /etc/timezone is a valid input
-    def timezone_valid_fake(filename, mode="r", open=open):
+    real_open = builtins.open
+    def timezone_valid_fake(filename, *args, **kw):
       if filename == "/etc/timezone":
         return StringIO("Australia/Sydney")
-      return open(filename, mode)
+      return real_open(filename, *args, **kw)
 
     self.mocked("builtins.open", timezone_valid_fake)
     tzinfo = datetime_tz._detect_timezone_etc_timezone()
     self.assertTimezoneEqual(tzinfo, pytz.timezone("Australia/Sydney"))
 
     # Check that when /etc/timezone is invalid timezone
-    def timezone_invalid_fake(filename, mode="r", open=open):
+    def timezone_invalid_fake(filename, *args, **kw):
       if filename == "/etc/timezone":
         return StringIO("Invalid-Timezone")
-      return open(filename, mode)
+      return real_open(filename, *args, **kw)
 
     self.mocked("builtins.open", timezone_invalid_fake)
     tzinfo = datetime_tz._detect_timezone_etc_timezone()
     self.assertEqual(None, tzinfo)
 
     # Check that when /etc/timezone is random "binary" data
-    def timezone_binary_fake(filename, mode="r", open=open):
+    def timezone_binary_fake(filename, *args, **kw):
       if filename == "/etc/timezone":
         return StringIO("\0\r\n\t\0\r\r\n\0")
-      return open(filename, mode)
+      return real_open(filename, *args, **kw)
 
     self.mocked("builtins.open", timezone_binary_fake)
     tzinfo = datetime_tz._detect_timezone_etc_timezone()
@@ -316,7 +317,8 @@ def os_walk_fake(dirname, *args, **kw):
       return os_walk(dirname, *args, **kw)
     self.mocked("os.walk", os_walk_fake)
 
-    def localtime_valid_fake(filename, mode="r", open=open):
+    real_open = builtins.open
+    def localtime_valid_fake(filename, *args, **kw):
       if filename == "/etc/localtime":
         filename = os.path.join(os.path.dirname(__file__),
                                 localtime_file)
@@ -331,7 +333,7 @@ def localtime_valid_fake(filename, mode="r", open=open):
           ):
         filename = os.path.join(os.path.dirname(__file__),
                                 "test_zonedata_utc")
-      return open(filename, mode)
+      return real_open(filename, *args, **kw)
     self.mocked("builtins.open", localtime_valid_fake)
 
     self.assertEqual(
@@ -1340,7 +1342,7 @@ def testDefaultTzinfos(self):
     self.assertTrue("Australia/Sydney" in def_tz.keys())
     self.assertTrue(def_tz.has_key("Australia/Sydney"))
     self.assertRaises(KeyError, def_tz.get, "Made/Up")
-    self.assertEquals(def_tz.get("Made/Up", None), None)
+    self.assertEqual(def_tz.get("Made/Up", None), None)
 
 
 class datetime_tz_test_subclass(datetime_tz.datetime_tz):
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..b9d1a9e
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,18 @@
+[tox]
+envlist = py27,
+          py36,
+          py37,
+          py38
+minversion = 3.3.0
+skip_missing_interpreters = true
+isolated_build = true
+
+[testenv]
+description = run the unit tests with pytest under {basepython}
+commands = pytest {posargs: --cov=datetime_tz} tests.py
+deps =
+  python-dateutil
+  pytz{env:PYTZ_VERSION:}
+  defusedxml
+  pytest
+  pytest-cov