diff --git a/.travis.yml b/.travis.yml
index 84cb0d7..8af51f1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,6 +2,7 @@ language: python
 python:
 - '2.7'
 - '3.5'
+- '3.6'
 env:
   global:
     - CC_TEST_REPORTER_ID=dc84306013e5ab029d115d8c2f9b27f23ee83b8d73c2dc35fed00954769fc76b
diff --git a/python_jsonschema_objects/classbuilder.py b/python_jsonschema_objects/classbuilder.py
index db31098..fa6b259 100644
--- a/python_jsonschema_objects/classbuilder.py
+++ b/python_jsonschema_objects/classbuilder.py
@@ -3,6 +3,7 @@ import python_jsonschema_objects.validators as validators
 import python_jsonschema_objects.pattern_properties as pattern_properties
 from python_jsonschema_objects.literals import LiteralValue
 
+import copy
 import collections
 import itertools
 import six
@@ -164,7 +165,9 @@ class ProtocolBase(collections.MutableMapping):
         # but only for the ones that have defaults set.
         for name in self.__has_default__:
             if name not in props:
-                default_value = self.__propinfo__[name]['default']
+                default_value = copy.deepcopy(
+                    self.__propinfo__[name]['default']
+                )
                 logger.debug(util.lazy_format("Initializing '{0}' to '{1}'",
                                               name, default_value))
                 setattr(self, name, default_value)
diff --git a/tox.ini b/tox.ini
index 1fd08be..4a88451 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 
 [tox]
-envlist = py27, py35
+envlist = py27, py35, py36
 
 [testenv]
 ;install_command = pip install {opts} {packages}

Instances of Generated Classes with Arrays Appear to be Global Across Class
I'm not entirely sure if I captured the problem concisely but here some example code the demonstrates the problem.

I have a simple schema that is as follows:
```
{
    "title": "Example Schema",
    "type": "object",
    "properties": {
        "a" :{
            "type": "array",
            "items": {
                "type": "string"
            },
            "default": []
        }
    }
}
```

I use said schema to create and use objects with the following code:
```python
import python_jsonschema_objects as pjs

ExampleClass = pjs.ObjectBuilder('./schema.json').build_classes().ExampleSchema
foo = ExampleClass()
foo.a.append('foo')
print foo.for_json()

bar = ExampleClass()
bar.a.append('bar')
print bar.for_json()
```

The output I receive is the following:
```
{u'a': ['foo']}
{u'a': ['foo', 'bar']}
```

Why does the `bar` object's a array contain the string `foo`.  What I would have expected is the following output:
```
{u'a': ['foo']}
{u'a': ['bar']}
```

I would have expected each instance of the `ExampleClass` to have independent array contents and them not to be shared.
diff --git a/test/test_regression_133.py b/test/test_regression_133.py
new file mode 100644
index 0000000..ac2cdbb
--- /dev/null
+++ b/test/test_regression_133.py
@@ -0,0 +1,27 @@
+
+import python_jsonschema_objects as pjs
+
+
+def test_nested_arrays_work_fine():
+    schema = {
+        "title": "Example Schema",
+        "type": "object",
+        "properties": {
+            "a": {"type": "array", "items": {"type": "string"}, "default": []}
+        },
+    }
+
+
+    ns1 = pjs.ObjectBuilder(schema).build_classes()
+
+    foo = ns1.ExampleSchema()
+    foo.a.append('foo')
+    print(foo.for_json())
+
+    assert foo.a == ['foo']
+
+    bar = ns1.ExampleSchema()
+    bar.a.append('bar')
+    print(bar.for_json())
+
+    assert bar.a == ['bar']

pip install -e .[dev]
parse_log_pytest
requirements.txt
nose rednose pyandoc pandoc sphinx sphinx-autobuild recommonmark pytest
3.5
requirements.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
alabaster==0.7.13
attrs==22.2.0
Babel==2.11.0
certifi==2021.5.30
charset-normalizer==2.0.12
colorama==0.4.5
commonmark==0.9.1
docutils==0.18.1
idna==3.10
imagesize==1.4.1
importlib-metadata==4.8.3
inflection==0.2.0
iniconfig==1.1.1
Jinja2==3.0.3
jsonschema==2.6.0
livereload==2.6.3
Markdown==2.4
MarkupSafe==2.0.1
nose==1.3.7
packaging==21.3
pandoc==2.4
pandocfilters==1.5.1
pluggy==1.0.0
plumbum==1.8.3
ply==3.11
py==1.11.0
pyandoc==0.2.0
Pygments==2.14.0
pyparsing==3.1.4
pyrsistent==0.18.0
pytest==7.0.1
-e git+https://github.com/cwacek/python-jsonschema-objects.git@66ab8b1c3a9e38ccc2d1d0f39db0d5c575ac42df#egg=python_jsonschema_objects
pytz==2025.2
recommonmark==0.7.1
rednose==1.3.0
requests==2.27.1
six==1.17.0
snowballstemmer==2.2.0
Sphinx==5.3.0
sphinx-autobuild==2021.3.14
sphinxcontrib-applehelp==1.0.2
sphinxcontrib-devhelp==1.0.2
sphinxcontrib-htmlhelp==2.0.0
sphinxcontrib-jsmath==1.0.1
sphinxcontrib-qthelp==1.0.3
sphinxcontrib-serializinghtml==1.1.5
termstyle==0.1.11
tomli==1.2.3
tornado==6.1
typing_extensions==4.1.1
urllib3==1.26.20
zipp==3.6.0

name: python-jsonschema-objects
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2021.5.30=py36h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.3=he6710b0_2
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - pip=21.2.2=py36h06a4308_0
  - python=3.6.13=h12debd9_1
  - readline=8.2=h5eee18b_0
  - setuptools=58.0.4=py36h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - wheel=0.37.1=pyhd3eb1b0_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - alabaster==0.7.13
      - attrs==22.2.0
      - babel==2.11.0
      - charset-normalizer==2.0.12
      - colorama==0.4.5
      - commonmark==0.9.1
      - docutils==0.18.1
      - idna==3.10
      - imagesize==1.4.1
      - importlib-metadata==4.8.3
      - inflection==0.2.0
      - iniconfig==1.1.1
      - jinja2==3.0.3
      - jsonschema==2.6.0
      - livereload==2.6.3
      - markdown==2.4
      - markupsafe==2.0.1
      - nose==1.3.7
      - packaging==21.3
      - pandoc==2.4
      - pandocfilters==1.5.1
      - pluggy==1.0.0
      - plumbum==1.8.3
      - ply==3.11
      - py==1.11.0
      - pyandoc==0.2.0
      - pygments==2.14.0
      - pyparsing==3.1.4
      - pyrsistent==0.18.0
      - pytest==7.0.1
      - pytz==2025.2
      - recommonmark==0.7.1
      - rednose==1.3.0
      - requests==2.27.1
      - six==1.17.0
      - snowballstemmer==2.2.0
      - sphinx==5.3.0
      - sphinx-autobuild==2021.3.14
      - sphinxcontrib-applehelp==1.0.2
      - sphinxcontrib-devhelp==1.0.2
      - sphinxcontrib-htmlhelp==2.0.0
      - sphinxcontrib-jsmath==1.0.1
      - sphinxcontrib-qthelp==1.0.3
      - sphinxcontrib-serializinghtml==1.1.5
      - termstyle==0.1.11
      - tomli==1.2.3
      - tornado==6.1
      - typing-extensions==4.1.1
      - urllib3==1.26.20
      - zipp==3.6.0
prefix: /opt/conda/envs/python-jsonschema-objects

test/test_regression_133.py::test_nested_arrays_work_fine
.travis.yml tox.ini python_jsonschema_objects/classbuilder.py
.travis.yml tox.ini python_jsonschema_objects/classbuilder.py