diff --git a/.travis.yml b/.travis.yml
index 9c50862..ca39904 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,15 +1,12 @@
 language: python
-python: 3.5
-env:
-  # Avoid testing pypy on travis until the following issue is fixed:
-  #   https://github.com/travis-ci/travis-ci/issues/4756
-  #- TOX_ENV=pypy
-  - TOX_ENV=py35
-  - TOX_ENV=py34
-  - TOX_ENV=py33
-  - TOX_ENV=py27
-  - TOX_ENV=docs
+python:
+  - pypy
+  - pypy3.5
+  - 2.7
+  - 3.4
+  - 3.5
+  - 3.6
 install:
-  - pip install coveralls tox
-script: tox -e  $TOX_ENV
+  - pip install coveralls tox-travis
+script: tox
 after_success: coveralls
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index db75618..c3184fd 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,3 +1,7 @@
+0.3.1 (2019-05-24)
+==================
+* Fix auth with newer versions of OAuth libraries while retaining backward compatibility
+
 0.3.0 (2017-01-24)
 ==================
 * Surface errors better
diff --git a/README.rst b/README.rst
index 90797ba..e1a576d 100644
--- a/README.rst
+++ b/README.rst
@@ -1,6 +1,8 @@
 python-fitbit
 =============
 
+.. image:: https://badge.fury.io/py/fitbit.svg
+    :target: https://badge.fury.io/py/fitbit
 .. image:: https://travis-ci.org/orcasgit/python-fitbit.svg?branch=master
    :target: https://travis-ci.org/orcasgit/python-fitbit
    :alt: Build Status
diff --git a/fitbit/__init__.py b/fitbit/__init__.py
index a19bb4a..0368d08 100644
--- a/fitbit/__init__.py
+++ b/fitbit/__init__.py
@@ -3,7 +3,7 @@
 Fitbit API Library
 ------------------
 
-:copyright: 2012-2017 ORCAS.
+:copyright: 2012-2019 ORCAS.
 :license: BSD, see LICENSE for more details.
 """
 
@@ -17,8 +17,8 @@
 __copyright__ = 'Copyright 2012-2017 ORCAS'
 __license__ = 'Apache 2.0'
 
-__version__ = '0.3.0'
-__release__ = '0.3.0'
+__version__ = '0.3.1'
+__release__ = '0.3.1'
 
 # Module namespace.
 
diff --git a/fitbit/api.py b/fitbit/api.py
index ba9d037..1b458b1 100644
--- a/fitbit/api.py
+++ b/fitbit/api.py
@@ -143,6 +143,7 @@ def fetch_access_token(self, code, redirect_uri=None):
             self.access_token_url,
             username=self.client_id,
             password=self.client_secret,
+            client_secret=self.client_secret,
             code=code)
 
     def refresh_token(self):
diff --git a/gather_keys_oauth2.py b/gather_keys_oauth2.py
index aade911..39a19f8 100755
--- a/gather_keys_oauth2.py
+++ b/gather_keys_oauth2.py
@@ -6,6 +6,7 @@
 import traceback
 import webbrowser
 
+from urllib.parse import urlparse
 from base64 import b64encode
 from fitbit.api import Fitbit
 from oauthlib.oauth2.rfc6749.errors import MismatchingStateError, MissingTokenError
@@ -28,6 +29,8 @@ def __init__(self, client_id, client_secret,
             timeout=10,
         )
 
+        self.redirect_uri = redirect_uri
+
     def browser_authorize(self):
         """
         Open a browser to the authorization url and spool up a CherryPy
@@ -36,6 +39,12 @@ def browser_authorize(self):
         url, _ = self.fitbit.client.authorize_token_url()
         # Open the web browser in a new thread for command-line browser support
         threading.Timer(1, webbrowser.open, args=(url,)).start()
+
+        # Same with redirect_uri hostname and port.
+        urlparams = urlparse(self.redirect_uri)
+        cherrypy.config.update({'server.socket_host': urlparams.hostname,
+                                'server.socket_port': urlparams.port})
+
         cherrypy.quickstart(self)
 
     @cherrypy.expose
diff --git a/setup.py b/setup.py
index c17939a..f5c4453 100644
--- a/setup.py
+++ b/setup.py
@@ -35,9 +35,9 @@
         'Programming Language :: Python',
         '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 :: Implementation :: PyPy'
     ),
 )
diff --git a/tox.ini b/tox.ini
index 279b114..71533b0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,25 +1,8 @@
 [tox]
-envlist = pypy,py35,py34,py33,py27,docs
+envlist = pypy-test,pypy3-test,py36-test,py35-test,py34-test,py27-test,py36-docs
 
 [testenv]
-commands = coverage run --source=fitbit setup.py test
+commands =
+  test: coverage run --source=fitbit setup.py test
+  docs: sphinx-build -W -b html docs docs/_build
 deps = -r{toxinidir}/requirements/test.txt
-
-[testenv:pypy]
-basepython = pypy
-
-[testenv:py35]
-basepython = python3.5
-
-[testenv:py34]
-basepython = python3.4
-
-[testenv:py33]
-basepython = python3.3
-
-[testenv:py27]
-basepython = python2.7
-
-[testenv:docs]
-basepython = python3.4
-commands = sphinx-build -W -b html docs docs/_build