diff --git a/pyhocon/config_tree.py b/pyhocon/config_tree.py
index 075bae1..354bfb6 100644
--- a/pyhocon/config_tree.py
+++ b/pyhocon/config_tree.py
@@ -93,7 +93,7 @@ class ConfigTree(OrderedDict):
                     self._push_history(key_elt, value)
                     self[key_elt] = value
                 elif isinstance(l, list):
-                    l += value
+                    self[key_elt] = l + value
                     self._push_history(key_elt, l)
                 elif l is None:
                     self._push_history(key_elt, value)
@@ -144,6 +144,8 @@ class ConfigTree(OrderedDict):
         if key_index == len(key_path) - 1:
             if isinstance(elt, NoneValue):
                 return None
+            elif isinstance(elt, list):
+                return [None if isinstance(x, NoneValue) else x for x in elt]
             else:
                 return elt
         elif isinstance(elt, ConfigTree):

diff --git a/tests/test_config_parser.py b/tests/test_config_parser.py
index ca08db6..8d9dffd 100644
--- a/tests/test_config_parser.py
+++ b/tests/test_config_parser.py
@@ -212,9 +212,11 @@ class TestConfigParser(object):
         config = ConfigFactory.parse_string(
             """
             a = null
+            b = [null]
             """
         )
         assert config.get('a') is None
+        assert config.get('b')[0] is None
 
     def test_parse_override(self):
         config = ConfigFactory.parse_string(
diff --git a/tests/test_config_tree.py b/tests/test_config_tree.py
index 97a8e17..3d194de 100644
--- a/tests/test_config_tree.py
+++ b/tests/test_config_tree.py
@@ -9,7 +9,7 @@ except ImportError:  # pragma: no cover
     from ordereddict import OrderedDict
 
 
-class TestConfigParser(object):
+class TestConfigTree(object):
 
     def test_config_tree_quoted_string(self):
         config_tree = ConfigTree()

get_list() returns NoneValue's, not None's
Given the following pyhocon file:
```
single_value = null
list_value = [null]
```

And the following code:
```python
from pyhocon import ConfigFactory
config = ConfigFactory.parse_file("test.conf")

single_value = config.get("single_value")
print single_value, single_value is None

list_value = config.get_list("list_value")[0]
print list_value, list_value is None

print single_value == list_value
``` 

You get as output:
```
None True
<pyhocon.config_tree.NoneValue object at 0xe20ad0> False
False
```

I expected both values to be Python's `None`.
tests/test_config_parser.py::TestConfigParser::test_parse_null
tests/test_config_tree.py::TestConfigTree::test_getter_type_conversion_number_to_string tests/test_config_tree.py::TestConfigTree::test_getter_type_conversion_string_to_bool tests/test_config_tree.py::TestConfigTree::test_config_logging tests/test_config_tree.py::TestConfigTree::test_overrides_int_with_config_append tests/test_config_tree.py::TestConfigTree::test_overrides_int_with_config_no_append tests/test_config_tree.py::TestConfigTree::test_getters tests/test_config_tree.py::TestConfigTree::test_contains tests/test_config_tree.py::TestConfigTree::test_getters_with_default tests/test_config_tree.py::TestConfigTree::test_config_tree_iterator tests/test_config_tree.py::TestConfigTree::test_config_list tests/test_config_tree.py::TestConfigTree::test_contains_with_quoted_keys tests/test_config_tree.py::TestConfigTree::test_configtree_pop tests/test_config_tree.py::TestConfigTree::test_keyerror_raised tests/test_config_tree.py::TestConfigTree::test_config_tree_number tests/test_config_tree.py::TestConfigTree::test_plain_ordered_dict tests/test_config_tree.py::TestConfigTree::test_getter_type_conversion_bool_to_string tests/test_config_tree.py::TestConfigTree::test_config_tree_quoted_string tests/test_config_tree.py::TestConfigTree::test_config_tree_null tests/test_config_parser.py::TestConfigParser::test_assign_dict_strings_no_equal_sign_with_eol tests/test_config_parser.py::TestConfigParser::test_cascade_string_substitutions tests/test_config_parser.py::TestConfigParser::test_include_missing_file tests/test_config_parser.py::TestConfigParser::test_list_element_substitution tests/test_config_parser.py::TestConfigParser::test_dos_chars_with_unquoted_string_noeol tests/test_config_parser.py::TestConfigParser::test_multiple_substitutions tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_dict_otherfield_merged_in tests/test_config_parser.py::TestConfigParser::test_from_dict_with_dict tests/test_config_parser.py::TestConfigParser::test_non_compatible_substitution tests/test_config_parser.py::TestConfigParser::test_multiline_with_backslash tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_dict_otherfield tests/test_config_parser.py::TestConfigParser::test_include_dict_from_samples tests/test_config_parser.py::TestConfigParser::test_missing_config tests/test_config_parser.py::TestConfigParser::test_fallback_substitutions_overwrite_file tests/test_config_parser.py::TestConfigParser::test_invalid_assignment tests/test_config_parser.py::TestConfigParser::test_substitution_list_with_append_substitution tests/test_config_parser.py::TestConfigParser::test_self_append_array tests/test_config_parser.py::TestConfigParser::test_list_of_lists tests/test_config_parser.py::TestConfigParser::test_concat_multi_line_list tests/test_config_parser.py::TestConfigParser::test_self_append_object tests/test_config_parser.py::TestConfigParser::test_non_existent_substitution tests/test_config_parser.py::TestConfigParser::test_self_append_nonexistent_object tests/test_config_parser.py::TestConfigParser::test_parse_with_comments tests/test_config_parser.py::TestConfigParser::test_include_required_file tests/test_config_parser.py::TestConfigParser::test_string_from_environment tests/test_config_parser.py::TestConfigParser::test_dict_substitutions tests/test_config_parser.py::TestConfigParser::test_list_of_dicts_with_merge tests/test_config_parser.py::TestConfigParser::test_with_comment_on_last_line tests/test_config_parser.py::TestConfigParser::test_triple_quotes_same_line tests/test_config_parser.py::TestConfigParser::test_bool_from_environment tests/test_config_parser.py::TestConfigParser::test_object_field_substitution tests/test_config_parser.py::TestConfigParser::test_list_substitutions tests/test_config_parser.py::TestConfigParser::test_concat_string tests/test_config_parser.py::TestConfigParser::test_dotted_notation_merge tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_dict_recurse_part tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_string_opt_concat tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_dict_otherfield_merged_in_mutual tests/test_config_parser.py::TestConfigParser::test_fallback_substitutions_overwrite tests/test_config_parser.py::TestConfigParser::test_from_dict_with_nested_dict tests/test_config_parser.py::TestConfigParser::test_concat_multi_line_string tests/test_config_parser.py::TestConfigParser::test_self_merge_ref_substitutions_object tests/test_config_parser.py::TestConfigParser::test_dos_chars_with_float_noeol tests/test_config_parser.py::TestConfigParser::test_string_substitutions tests/test_config_parser.py::TestConfigParser::test_list_of_dicts tests/test_config_parser.py::TestConfigParser::test_optional_substitution tests/test_config_parser.py::TestConfigParser::test_fallback_self_ref_substitutions_merge tests/test_config_parser.py::TestConfigParser::test_self_append_string tests/test_config_parser.py::TestConfigParser::test_dos_chars_with_quoted_string_noeol tests/test_config_parser.py::TestConfigParser::test_object_concat tests/test_config_parser.py::TestConfigParser::test_substitution_flat_override tests/test_config_parser.py::TestConfigParser::test_parse_override tests/test_config_parser.py::TestConfigParser::test_self_merge_ref_substitutions_object2 tests/test_config_parser.py::TestConfigParser::test_string_substitutions_with_no_space tests/test_config_parser.py::TestConfigParser::test_concat_list tests/test_config_parser.py::TestConfigParser::test_assign_strings_with_eol tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_dict_path_hide tests/test_config_parser.py::TestConfigParser::test_int_substitutions tests/test_config_parser.py::TestConfigParser::test_quoted_unquoted_strings_with_ws tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_array tests/test_config_parser.py::TestConfigParser::test_parse_simple_value tests/test_config_parser.py::TestConfigParser::test_substitution_override tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_array_to_dict tests/test_config_parser.py::TestConfigParser::test_substitutions_overwrite tests/test_config_parser.py::TestConfigParser::test_int_from_environment tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_dict_recurse2 tests/test_config_parser.py::TestConfigParser::test_parse_URL_from_samples tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_object tests/test_config_parser.py::TestConfigParser::test_assign_next_line tests/test_config_parser.py::TestConfigParser::test_self_ref_substitiotion_dict_in_array tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_dict_path tests/test_config_parser.py::TestConfigParser::test_assign_dict_strings_with_equal_sign_with_eol tests/test_config_parser.py::TestConfigParser::test_assign_list_numbers_with_eol tests/test_config_parser.py::TestConfigParser::test_self_append_non_existent_string tests/test_config_parser.py::TestConfigParser::test_list_of_lists_with_merge tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_dict_recurse tests/test_config_parser.py::TestConfigParser::test_multi_line_escape tests/test_config_parser.py::TestConfigParser::test_concat_dict tests/test_config_parser.py::TestConfigParser::test_var_with_include_keyword tests/test_config_parser.py::TestConfigParser::test_quoted_key_with_dots tests/test_config_parser.py::TestConfigParser::test_include_substitution tests/test_config_parser.py::TestConfigParser::test_fallback_self_ref_substitutions_concat_string tests/test_config_parser.py::TestConfigParser::test_assign_list_strings_with_eol tests/test_config_parser.py::TestConfigParser::test_self_append_nonexistent_array tests/test_config_parser.py::TestConfigParser::test_self_merge_ref_substitutions_object3 tests/test_config_parser.py::TestConfigParser::test_cascade_optional_substitution tests/test_config_parser.py::TestConfigParser::test_parse_with_enclosing_brace tests/test_config_parser.py::TestConfigParser::test_pop tests/test_config_parser.py::TestConfigParser::test_unicode_dict_key tests/test_config_parser.py::TestConfigParser::test_dict_merge tests/test_config_parser.py::TestConfigParser::test_substitution_cycle tests/test_config_parser.py::TestConfigParser::test_comma_to_separate_expr tests/test_config_parser.py::TestConfigParser::test_dos_chars_with_triple_quoted_string_noeol tests/test_config_parser.py::TestConfigParser::test_include_missing_required_file tests/test_config_parser.py::TestConfigParser::test_plain_ordered_dict tests/test_config_parser.py::TestConfigParser::test_quoted_unquoted_strings_with_ws_substitutions tests/test_config_parser.py::TestConfigParser::test_unquoted_strings_with_ws tests/test_config_parser.py::TestConfigParser::test_parse_with_enclosing_square_bracket tests/test_config_parser.py::TestConfigParser::test_parse_URL_from_invalid tests/test_config_parser.py::TestConfigParser::test_quoted_strings_with_ws tests/test_config_parser.py::TestConfigParser::test_include_file tests/test_config_parser.py::TestConfigParser::test_from_dict_with_ordered_dict tests/test_config_parser.py::TestConfigParser::test_assign_number_with_eol tests/test_config_parser.py::TestConfigParser::test_include_dict tests/test_config_parser.py::TestConfigParser::test_invalid_dict tests/test_config_parser.py::TestConfigParser::test_issue_75 tests/test_config_parser.py::TestConfigParser::test_fallback_self_ref_substitutions_append tests/test_config_parser.py::TestConfigParser::test_substitution_nested_override tests/test_config_parser.py::TestConfigParser::test_fallback_self_ref_substitutions_append_plus_equals tests/test_config_parser.py::TestConfigParser::test_one_line_quote_escape tests/test_config_parser.py::TestConfigParser::test_dos_chars_with_int_noeol tests/test_config_parser.py::TestConfigParser::test_concat_multi_line_dict tests/test_config_parser.py::TestConfigParser::test_bad_concat tests/test_config_parser.py::TestConfigParser::test_substitution_list_with_append tests/test_config_parser.py::TestConfigParser::test_self_ref_substitution_dict_merge