diff --git a/circle.yml b/circle.yml
index 74a2f68584a..f4909428b1d 100644
--- a/circle.yml
+++ b/circle.yml
@@ -7,14 +7,20 @@ machine:
     PLOTLY_OPTIONAL_REQUIREMENTS_FILE: ${PLOTLY_PACKAGE_ROOT}/optional-requirements.txt
     PLOTLY_OPTIONAL_REQUIREMENTS_FILE_2_6: ${PLOTLY_PACKAGE_ROOT}/optional-requirements-2-6.txt
 dependencies:
-  pre:
+  override:
+
     # run all the pre-written installers (this will take a *while*)
     - bash circle/setup.sh
+
     # install testing tools for circle's version of things
-    - PYENV_VERSION=2.7 && pip install nose coverage
-  override:
-    - PYENV_VERSION=2.7 && pip install -I .
-    - PYENV_VERSION=2.7 && cd ~ && python -c "import plotly"
+    - pip install nose coverage
+    - pip install -I .
+
+    # we need to cd out of the project root to ensure the install worked
+    - cd ~ && python -c "import plotly"
+
+  cache_directories:
+    - "~/.pyenv/versions"  # attempt to just cache installed pyenv things
 test:
   override:
 
@@ -28,6 +34,6 @@ test:
 #    - sudo chmod 600 ${PLOTLY_CONFIG_DIR} && python -c "import plotly"
 
     # test core things in the general 2.7 version that circle has
-    - PYENV_VERSION=2.7 && nosetests -xv plotly/tests --with-coverage --cover-package=plotly
+    - nosetests -xv plotly/tests --with-coverage --cover-package=plotly
     - mkdir "${CIRCLE_ARTIFACTS}/2.7" || true
     - coverage html -d "${CIRCLE_ARTIFACTS}/2.7" --title=2.7
diff --git a/circle/setup.sh b/circle/setup.sh
index d5e715dc95b..84281f1490c 100644
--- a/circle/setup.sh
+++ b/circle/setup.sh
@@ -12,6 +12,10 @@ function error_exit
     exit 1
 }
 
+# PYENV shims need to be infront of the rest of the path to work!
+echo "adding pyenv shims to the beginning of the path in this shell"
+export PATH="/home/ubuntu/.pyenv/shims:$PATH"
+
 # for each version we want, setup a functional virtual environment
 for version in ${PLOTLY_PYTHON_VERSIONS[@]}; do
     echo Setting up Python ${version}
@@ -20,6 +24,11 @@ for version in ${PLOTLY_PYTHON_VERSIONS[@]}; do
     export PYENV_VERSION=${version}
     echo "Using pyenv version $(pyenv version)"
 
+    # this was a major issue previously, sanity check that we're using the
+    # version we *think* we're using (that pyenv is pointing to)
+    echo "python -c 'import sys; print(sys.version)'"
+    python -c 'import sys; print(sys.version)'
+
     # install core requirements all versions need
     pip install -r ${PLOTLY_CORE_REQUIREMENTS_FILE} ||
         error_exit "${LINENO}: can't install core reqs for Python ${version}"
diff --git a/circle/test.sh b/circle/test.sh
index 11dd86c60d1..b31775d5d42 100644
--- a/circle/test.sh
+++ b/circle/test.sh
@@ -12,6 +12,10 @@ function error_exit
     exit 1
 }
 
+# PYENV shims need to be infront of the rest of the path to work!
+echo "adding pyenv shims to the beginning of the path in this shell"
+export PATH="/home/ubuntu/.pyenv/shims:$PATH"
+
 # for each version we want, setup a functional virtual environment
 for version in ${PLOTLY_PYTHON_VERSIONS[@]}; do
     echo Testing Python ${version}
@@ -20,6 +24,12 @@ for version in ${PLOTLY_PYTHON_VERSIONS[@]}; do
     export PYENV_VERSION=${version}
     echo "Using pyenv version $(pyenv version)"
 
+    # this was a major issue previously, sanity check that we're using the
+    # version we *think* we're using (that pyenv is pointing to)
+    echo "python -c 'import sys; print(sys.version)'"
+    python -c 'import sys; print(sys.version)'
+
+
     echo "install plotly (ignoring possibly cached versions)"
     pip install -I ${PLOTLY_PACKAGE_ROOT} ||
         error_exit "${LINENO}: can't install plotly package from project root"
diff --git a/plotly/exceptions.py b/plotly/exceptions.py
index c98e630fc58..ff25df04427 100644
--- a/plotly/exceptions.py
+++ b/plotly/exceptions.py
@@ -15,9 +15,14 @@
 
 
 """
-import json
+import sys
 import six
 
+if sys.version[:3] == '2.6':
+    import simplejson as json
+else:
+    import json
+
 ## Base Plotly Error ##
 
 class PlotlyError(Exception):
@@ -49,7 +54,10 @@ def __init__(self, requests_exception):
         elif content_type == 'text/plain':
             self.message = requests_exception.response.content
         else:
-            self.message = requests_exception.message
+            try:
+                self.message = requests_exception.message
+            except AttributeError:
+                self.message = 'unknown error'
 
     def __str__(self):
         return self.message
diff --git a/plotly/grid_objs/grid_objs.py b/plotly/grid_objs/grid_objs.py
index fcba45d4df9..8dc8faaab90 100644
--- a/plotly/grid_objs/grid_objs.py
+++ b/plotly/grid_objs/grid_objs.py
@@ -5,12 +5,16 @@
 """
 from __future__ import absolute_import
 
-
-import json
+import sys
 from collections import MutableSequence
 from plotly import exceptions
 from plotly import utils
 
+if sys.version[:3] == '2.6':
+    import simplejson as json
+else:
+    import json
+
 __all__ = None
 
 
diff --git a/plotly/plotly/plotly.py b/plotly/plotly/plotly.py
index b2e44e19ce0..72b5ee42644 100644
--- a/plotly/plotly/plotly.py
+++ b/plotly/plotly/plotly.py
@@ -17,7 +17,6 @@
 from __future__ import absolute_import
 
 import sys
-import json
 import warnings
 import copy
 import os
@@ -30,6 +29,11 @@
 else:
     from urllib.parse import urlparse
 
+if sys.version[:3] == '2.6':
+    import simplejson as json
+else:
+    import json
+
 from plotly.plotly import chunked_requests
 from plotly import utils
 from plotly import tools
diff --git a/plotly/tests/test_core/test_get_figure/test_get_figure.py b/plotly/tests/test_core/test_get_figure/test_get_figure.py
index 0fc86f49241..85a92d264a4 100644
--- a/plotly/tests/test_core/test_get_figure/test_get_figure.py
+++ b/plotly/tests/test_core/test_get_figure/test_get_figure.py
@@ -10,10 +10,10 @@
 from plotly import exceptions
 from nose.tools import raises
 import six
-import json
 
 from unittest import TestCase
-from unittest import skipIf
+
+version = six.sys.version_info[:2]  # need this for conditional testing
 
 
 # username for tests: 'plotlyimagetest'
@@ -198,12 +198,18 @@ def test_all():
 
 class TestBytesVStrings(TestCase):
 
-    @skipIf(not six.PY3, 'Decoding and missing escapes is only seen in PY3')
-    def test_proper_escaping(self):
-        un = 'PlotlyImageTest'
-        ak = '786r5mecv0'
-        url = "https://plot.ly/~PlotlyImageTest/91/"
-        py.sign_in(un, ak)
-        print("getting: https://plot.ly/~PlotlyImageTest/91/")
-        print("###########################################\n\n")
-        fig = py.get_figure(url)
+    # unittest `skipIf` not supported in 2.6
+    if version < (2, 7) or (2, 7) < version < (3, 3):
+        pass
+    else:
+        from unittest import skipIf
+
+        @skipIf(not six.PY3, 'Decoding and missing escapes only seen in PY3')
+        def test_proper_escaping(self):
+            un = 'PlotlyImageTest'
+            ak = '786r5mecv0'
+            url = "https://plot.ly/~PlotlyImageTest/91/"
+            py.sign_in(un, ak)
+            print("getting: https://plot.ly/~PlotlyImageTest/91/")
+            print("###########################################\n\n")
+            fig = py.get_figure(url)
diff --git a/plotly/tests/test_core/test_get_requests/test_get_requests.py b/plotly/tests/test_core/test_get_requests/test_get_requests.py
index c40f15a951d..473fcd15ceb 100644
--- a/plotly/tests/test_core/test_get_requests/test_get_requests.py
+++ b/plotly/tests/test_core/test_get_requests/test_get_requests.py
@@ -8,8 +8,13 @@
 
 import requests
 import copy
-import json
 import six
+import sys
+
+if sys.version[:3] == '2.6':
+    import simplejson as json
+else:
+    import json
 
 default_headers = {'plotly-username': '',
                    'plotly-apikey': '',
diff --git a/plotly/tests/test_core/test_utils/test_utils.py b/plotly/tests/test_core/test_utils/test_utils.py
index 5f0a62d88ed..94be40b3949 100644
--- a/plotly/tests/test_core/test_utils/test_utils.py
+++ b/plotly/tests/test_core/test_utils/test_utils.py
@@ -1,8 +1,13 @@
-import json
+import sys
 from unittest import TestCase
 
 from plotly.utils import PlotlyJSONEncoder
 
+if sys.version[:3] == '2.6':
+    import simplejson as json
+else:
+    import json
+
 
 class TestJSONEncoder(TestCase):
 
diff --git a/plotly/tests/test_optional/test_ipython/test_embed.py b/plotly/tests/test_optional/test_ipython/test_embed.py
index 587b3f20a8e..f9a69527828 100644
--- a/plotly/tests/test_optional/test_ipython/test_embed.py
+++ b/plotly/tests/test_optional/test_ipython/test_embed.py
@@ -5,13 +5,14 @@
 import threading
 import six
 import unittest
-from unittest import skip
 version = six.sys.version_info[:2]  # need this for conditional testing
 
 # unittest `skipIf` not supported in 2.6 and IPython not supported in 2.6/3.2
 if version < (2, 7) or (2, 7) < version < (3, 3):
     pass
 else:
+    from unittest import skip
+
     @skip
     class TestPlotlyDisplay(unittest.TestCase):
 
diff --git a/plotly/tests/test_optional/test_ipython/test_widgets.py b/plotly/tests/test_optional/test_ipython/test_widgets.py
index 6d54403065b..e3b45761da0 100644
--- a/plotly/tests/test_optional/test_ipython/test_widgets.py
+++ b/plotly/tests/test_optional/test_ipython/test_widgets.py
@@ -1,9 +1,16 @@
+import six
 from unittest import TestCase
 
-from plotly.widgets import GraphWidget
+version = six.sys.version_info[:2]  # need this for conditional testing
 
+# unittest `skip` not supported in 2.6 and IPython not supported in 2.6/3.2
+if version < (2, 7) or (2, 7) < version < (3, 3):
+    pass
+else:
+    from plotly.widgets import GraphWidget
 
-class TestWidgets(TestCase):
 
-    def test_instantiate_graph_widget(self):
-        widget = GraphWidget
+    class TestWidgets(TestCase):
+
+        def test_instantiate_graph_widget(self):
+            widget = GraphWidget
diff --git a/plotly/tests/test_optional/test_matplotlylib/test_date_times.py b/plotly/tests/test_optional/test_matplotlylib/test_date_times.py
index 75ff1605d26..5e05f3ba4fc 100644
--- a/plotly/tests/test_optional/test_matplotlylib/test_date_times.py
+++ b/plotly/tests/test_optional/test_matplotlylib/test_date_times.py
@@ -64,4 +64,4 @@ def test_pandas_time_series_date_formatter(self):
 
         x0 = fig.axes[0].lines[0].get_xydata()[0][0]
         self.assertEqual(x0, expected_x0)
-        self.assertListEqual(pfig['data'][0]['x'], expected_x)
+        self.assertEqual(pfig['data'][0]['x'], expected_x)
diff --git a/plotly/tests/test_optional/test_utils/test_utils.py b/plotly/tests/test_optional/test_utils/test_utils.py
index a1450913860..db3d8dc3f56 100644
--- a/plotly/tests/test_optional/test_utils/test_utils.py
+++ b/plotly/tests/test_optional/test_utils/test_utils.py
@@ -11,6 +11,7 @@
 import numpy as np
 import json
 import pandas as pd
+import sys
 from pandas.util.testing import assert_series_equal
 import matplotlib.pyplot as plt
 
@@ -27,7 +28,7 @@ def test_encode_as_plotly(self):
 
         # should *fail* when object doesn't have `to_plotly_json` attribute
         objs_without_attr = [
-            1, 'one', {'a', 'set'}, {'a': 'dict'}, ['a', 'list']
+            1, 'one', set(['a', 'set']), {'a': 'dict'}, ['a', 'list']
         ]
         for obj in objs_without_attr:
             self.assertRaises(utils.NotEncodable,
@@ -48,7 +49,7 @@ def test_encode_as_list(self):
 
         # should *fail* when object doesn't have `tolist` method
         objs_without_attr = [
-            1, 'one', {'a', 'set'}, {'a': 'dict'}, ['a', 'list']
+            1, 'one', set(['a', 'set']), {'a': 'dict'}, ['a', 'list']
         ]
         for obj in objs_without_attr:
             self.assertRaises(utils.NotEncodable,
@@ -75,7 +76,7 @@ def test_encode_as_pandas(self):
 
         # should succeed when we've got specific pandas thingies
         res = utils.PlotlyJSONEncoder.encode_as_pandas(pd.NaT)
-        self.assertIs(res, None)
+        self.assertTrue(res is None)
 
     def test_encode_as_numpy(self):
 
@@ -132,7 +133,7 @@ def test_encode_as_date(self):
                               utils.PlotlyJSONEncoder.encode_as_date, obj)
 
         # should work with a date
-        a_date = datetime.date(2013, 10, 01)
+        a_date = datetime.date(2013, 10, 1)
         res = utils.PlotlyJSONEncoder.encode_as_date(a_date)
         self.assertEqual(res, '2013-10-01')
 
@@ -248,9 +249,8 @@ def test_pandas_json_encoding():
 def test_numpy_masked_json_encoding():
     l = [1, 2, np.ma.core.masked]
     j1 = json.dumps(l, cls=utils.PlotlyJSONEncoder)
-    print j1
+    print(j1)
     assert(j1 == '[1, 2, null]')
-    assert(set(l) == set([1, 2, np.ma.core.masked]))
 
 
 def test_masked_constants_example():
@@ -275,8 +275,9 @@ def test_masked_constants_example():
 
     jy = json.dumps(renderer.plotly_fig['data'][1]['y'],
                     cls=utils.PlotlyJSONEncoder)
-    assert(jy == '[-398.11793026999999, -398.11792966000002, '
-                 '-398.11786308000001, null]')
+    print(jy)
+    array = json.loads(jy)
+    assert(array == [-398.11793027, -398.11792966, -398.11786308, None])
 
 
 def test_numpy_dates():
diff --git a/plotly/utils.py b/plotly/utils.py
index e948a07507f..c8a38aceabc 100644
--- a/plotly/utils.py
+++ b/plotly/utils.py
@@ -6,7 +6,6 @@
 
 """
 
-import json
 import os.path
 import sys
 import threading
@@ -32,6 +31,11 @@
 except ImportError:
     _sage_imported = False
 
+if sys.version[:3] == '2.6':
+    import simplejson as json
+else:
+    import json
+
 
 ### incase people are using threading, we lock file reads
 lock = threading.Lock()
@@ -124,66 +128,45 @@ class PlotlyJSONEncoder(json.JSONEncoder):
     version.
 
     """
+    def coerce_to_strict(self, const):
+        """
+        This is used to ultimately *encode* into strict JSON, see `encode`
 
-    # we want stricter JSON, so convert NaN, Inf, -Inf --> 'null'
-    nan_str = inf_str = neg_inf_str = 'null'
-
-    # uses code from official python json.encoder module. Same licence applies.
-    def iterencode(self, o, _one_shot=False):
         """
-        Encode the given object and yield each string
-        representation as available.
+        # before python 2.7, 'true', 'false', 'null', were include here.
+        if const in ('Infinity', '-Infinity', 'NaN'):
+            return None
+        else:
+            return const
 
-        For example::
+    def encode(self, o):
+        """
+        Load and then dump the result using parse_constant kwarg
 
-            for chunk in JSONEncoder().iterencode(bigobject):
-                mysocket.write(chunk)
+        Note that setting invalid separators will cause a failure at this step.
 
         """
-        if self.check_circular:
-            markers = {}
-        else:
-            markers = None
-        if self.ensure_ascii:
-            _encoder = json.encoder.encode_basestring_ascii
-        else:
-            _encoder = json.encoder.encode_basestring
-        if self.encoding != 'utf-8':
-            def _encoder(o, _orig_encoder=_encoder, _encoding=self.encoding):
-                if isinstance(o, str):
-                    o = o.decode(_encoding)
-                return _orig_encoder(o)
-
-        def floatstr(o, allow_nan=self.allow_nan,
-                     _repr=json.encoder.FLOAT_REPR, _inf=json.encoder.INFINITY,
-                     _neginf=-json.encoder.INFINITY):
-            # Check for specials.  Note that this type of test is processor
-            # and/or platform-specific, so do tests which don't depend on the
-            # internals.
-
-            # *any* two NaNs are not equivalent (even to itself) try:
-            # float('NaN') == float('NaN')
-            if o != o:
-                text = self.nan_str
-            elif o == _inf:
-                text = self.inf_str
-            elif o == _neginf:
-                text = self.neg_inf_str
-            else:
-                return _repr(o)
 
-            if not allow_nan:
-                raise ValueError(
-                    "Out of range float values are not JSON compliant: " +
-                    repr(o))
+        # this will raise errors in a normal-expected way
+        encoded_o = super(PlotlyJSONEncoder, self).encode(o)
 
-            return text
+        # now:
+        #    1. `loads` to switch Infinity, -Infinity, NaN to None
+        #    2. `dumps` again so you get 'null' instead of extended JSON
+        try:
+            new_o = json.loads(encoded_o, parse_constant=self.coerce_to_strict)
+        except ValueError:
 
-        _iterencode = json.encoder._make_iterencode(
-                markers, self.default, _encoder, self.indent, floatstr,
-                self.key_separator, self.item_separator, self.sort_keys,
-                self.skipkeys, _one_shot)
-        return _iterencode(o, 0)
+            # invalid separators will fail here. raise a helpful exception
+            raise ValueError(
+                "Encoding into strict JSON failed. Did you set the separators "
+                "valid JSON separators?"
+            )
+        else:
+            return json.dumps(new_o, sort_keys=self.sort_keys,
+                              indent=self.indent,
+                              separators=(self.item_separator,
+                                          self.key_separator))
 
     def default(self, obj):
         """
diff --git a/plotly/version.py b/plotly/version.py
index 9a5e84e0a7a..e226d1e9f91 100644
--- a/plotly/version.py
+++ b/plotly/version.py
@@ -1 +1 @@
-__version__ = '1.6.11'
+__version__ = '1.6.12'
diff --git a/plotly/widgets/graph_widget.py b/plotly/widgets/graph_widget.py
index 22c5c28434f..89e22769170 100644
--- a/plotly/widgets/graph_widget.py
+++ b/plotly/widgets/graph_widget.py
@@ -1,6 +1,6 @@
 from collections import deque
-import json
 import uuid
+import sys
 
 # TODO: protected imports?
 from IPython.html import widgets
@@ -11,6 +11,12 @@
 from plotly.graph_objs import Figure
 from pkg_resources import resource_string
 
+# even though python 2.6 wouldn't be able to run *any* of this...
+if sys.version[:3] == '2.6':
+    import simplejson as json
+else:
+    import json
+
 # Load JS widget code
 # No officially recommended way to do this in any other way
 # http://mail.scipy.org/pipermail/ipython-dev/2014-April/013835.html