diff --git a/.travis.yml b/.travis.yml
index 01bdbd682..c050aced8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -30,6 +30,7 @@ addons:
     - aspell-en
 
 install:
+  - pip install 'setuptools>=36'
   - pip install tox
   - pip install 'coverage<4.0'
   - pip install codecov
diff --git a/markdown/__init__.py b/markdown/__init__.py
index 80434e96c..b39202d6b 100644
--- a/markdown/__init__.py
+++ b/markdown/__init__.py
@@ -23,36 +23,42 @@
 from __future__ import absolute_import
 from __future__ import unicode_literals
 from .core import Markdown, markdown, markdownFromFile
+from pkg_resources.extern import packaging
 
 # For backward compatibility as some extensions expect it...
 from .extensions import Extension  # noqa
 
 __all__ = ['Markdown', 'markdown', 'markdownFromFile']
 
-# version_info should conform to PEP 386
-# (major, minor, micro, alpha/beta/rc/final, #)
-# (1, 1, 2, 'alpha', 0) => "1.1.2.dev"
+# version must conform to PEP 440
+# https://www.python.org/dev/peps/pep-0440/
+
+# __version_info__ format:
+# (major, minor, patch, dev/alpha/beta/rc/final, #)
+# (1, 1, 2, 'dev', 0) => "1.1.2.dev0"
+# (1, 1, 2, 'alpha', 1) => "1.1.2a1"
 # (1, 2, 0, 'beta', 2) => "1.2b2"
-__version_info__ = (3, 0, 1, 'final', 0)
+# (1, 2, 0, 'rc', 4) => "1.2rc4"
+# (1, 2, 0, 'final', 0) => "1.2"
+__version_info__ = (3, 1, 0, 'dev', 0)
 
 
 def _get_version():  # pragma: no cover
-    " Returns a PEP 386-compliant version number from version_info. "
+    " Returns a PEP 440-compliant version number from version_info. "
     assert len(__version_info__) == 5
-    assert __version_info__[3] in ('alpha', 'beta', 'rc', 'final')
+    assert __version_info__[3] in ('dev', 'alpha', 'beta', 'rc', 'final')
 
     parts = 2 if __version_info__[2] == 0 else 3
-    main = '.'.join(map(str, __version_info__[:parts]))
+    v = '.'.join(map(str, __version_info__[:parts]))
 
-    sub = ''
-    if __version_info__[3] == 'alpha' and __version_info__[4] == 0:
-        # TODO: maybe append some sort of git info here??
-        sub = '.dev'
+    if __version_info__[3] == 'dev':
+        v += '.dev' + str(__version_info__[4])
     elif __version_info__[3] != 'final':
-        mapping = {'alpha': 'a', 'beta': 'b', 'rc': 'c'}
-        sub = mapping[__version_info__[3]] + str(__version_info__[4])
+        mapping = {'alpha': 'a', 'beta': 'b', 'rc': 'rc'}
+        v += mapping[__version_info__[3]] + str(__version_info__[4])
 
-    return str(main + sub)
+    # Ensure version is valid and normalized
+    return str(packaging.version.Version(v))
 
 
 __version__ = _get_version()
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 000000000..a1d0683e2
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,4 @@
+[build-system]
+# Minimum requirements for the build system to execute.
+requires = ["setuptools>=36", "wheel"]
+build-backend = "setuptools.build_meta"
diff --git a/setup.py b/setup.py
index f906389f4..938defa20 100755
--- a/setup.py
+++ b/setup.py
@@ -28,15 +28,13 @@
 
 # Get development Status for classifiers
 dev_status_map = {
+    'dev':   '2 - Pre-Alpha',
     'alpha': '3 - Alpha',
     'beta':  '4 - Beta',
     'rc':    '4 - Beta',
     'final': '5 - Production/Stable'
 }
-if __version_info__[3] == 'alpha' and __version_info__[4] == 0:
-    DEVSTATUS = '2 - Pre-Alpha'
-else:
-    DEVSTATUS = dev_status_map[__version_info__[3]]
+DEVSTATUS = dev_status_map[__version_info__[3]]
 
 # The command line script name.  Currently set to "markdown_py" so as not to
 # conflict with the perl implimentation (which uses "markdown").
@@ -79,6 +77,7 @@
     license='BSD License',
     packages=['markdown', 'markdown.extensions'],
     python_requires='>=2.7,!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*',
+    install_requires=['setuptools >= 36'],
     entry_points={
         'console_scripts': [
             '%s = markdown.__main__:run' % SCRIPT_NAME,
diff --git a/tox.ini b/tox.ini
index 42cdd50c3..0e130aebf 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,8 +1,13 @@
 [tox]
 envlist = py27, py34, py35, py36, py37, pypy, pypy3, flake8, checkspelling
+requires = setuptools>=36
+isolated_build = True
 
 [testenv]
-deps = -rtest-requirements.txt
+deps =
+    coverage<4.0
+    pyyaml
+    pytidylib
 commands = coverage run --source=markdown -m unittest discover {toxinidir}/tests
            coverage report --show-missing