diff --git a/.gitignore b/.gitignore
index c5e9682..5503138 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 *.py[co]
 .*.sw?
+.DS_Store
 /reclass-config.yml
 /reclass.egg-info
 /build
diff --git a/reclass/__init__.py b/reclass/__init__.py
index adb421e..a79c8e1 100644
--- a/reclass/__init__.py
+++ b/reclass/__init__.py
@@ -11,6 +11,7 @@
 from reclass.storage.loader import StorageBackendLoader
 from reclass.storage.memcache_proxy import MemcacheProxy
 
+
 def get_storage(storage_type, nodes_uri, classes_uri, **kwargs):
     storage_class = StorageBackendLoader(storage_type).load()
     return MemcacheProxy(storage_class(nodes_uri, classes_uri, **kwargs))
diff --git a/reclass/adapters/ansible.py b/reclass/adapters/ansible.py
index 1887245..f6e9af3 100755
--- a/reclass/adapters/ansible.py
+++ b/reclass/adapters/ansible.py
@@ -16,6 +16,8 @@
 
 import os, sys, posix, optparse
 
+from six import iteritems
+
 from reclass import get_storage, output
 from reclass.core import Core
 from reclass.errors import ReclassException
@@ -81,7 +83,7 @@
             apps = data['applications']
             if options.applications_postfix:
                 postfix = options.applications_postfix
-                groups.update([(k + postfix, v) for k,v in apps.iteritems()])
+                groups.update([(k + postfix, v) for (k, v) in iteritems(apps)])
             else:
                 groups.update(apps)
 
diff --git a/reclass/adapters/salt.py b/reclass/adapters/salt.py
index 54adf5a..31179ff 100755
--- a/reclass/adapters/salt.py
+++ b/reclass/adapters/salt.py
@@ -9,6 +9,8 @@
 
 import os, sys, posix
 
+from six import iteritems
+
 from reclass import get_storage, output, get_path_mangler
 from reclass.core import Core
 from reclass.errors import ReclassException
@@ -68,7 +70,7 @@
     else:
         data = reclass.inventory()
         nodes = {}
-        for node_id, node_data in data['nodes'].iteritems():
+        for (node_id, node_data) in iteritems(data['nodes']):
             env = node_data['environment']
             if env not in nodes:
                 nodes[env] = {}
diff --git a/reclass/core.py b/reclass/core.py
index 9da0ddb..9a23d89 100644
--- a/reclass/core.py
+++ b/reclass/core.py
@@ -15,11 +15,19 @@
 import string
 import sys
 import yaml
+
+from six import iteritems
+
 from reclass.settings import Settings
 from reclass.output.yaml_outputter import ExplicitDumper
 from reclass.datatypes import Entity, Classes, Parameters, Exports
 from reclass.errors import MappingFormatError, ClassNotFound, InvQueryClassNotFound, InvQueryError, InterpolationError
 
+try:
+    basestring
+except NameError:
+    basestring = str
+
 class Core(object):
 
     def __init__(self, storage, class_mappings, settings, input_data=None):
@@ -54,7 +62,7 @@
             regexp = True
         try:
             key = lexer.get_token()
-        except ValueError, e:
+        except ValueError as e:
             raise MappingFormatError('Error in mapping "{0}": missing closing '
                                      'quote (or slash)'.format(instr))
         if regexp:
@@ -128,7 +136,7 @@
 
     def _get_automatic_parameters(self, nodename, environment):
         if self._settings.automatic_parameters:
-            return Parameters({ '_reclass_': { 'name': { 'full': nodename, 'short': string.split(nodename, '.')[0] },
+            return Parameters({ '_reclass_': { 'name': { 'full': nodename, 'short': str.split(nodename, '.')[0] },
                                                'environment': environment } }, self._settings, '__auto__')
         else:
             return Parameters({}, self._settings, '')
@@ -220,7 +228,7 @@
         nodes = {}
         applications = {}
         classes = {}
-        for f, nodeinfo in entities.iteritems():
+        for (f, nodeinfo) in iteritems(entities):
             d = nodes[f] = self._nodeinfo_as_dict(f, nodeinfo)
             for a in d['applications']:
                 if a in applications:
diff --git a/reclass/datatypes/classes.py b/reclass/datatypes/classes.py
index b8793a2..090ed70 100644
--- a/reclass/datatypes/classes.py
+++ b/reclass/datatypes/classes.py
@@ -7,12 +7,13 @@
 # Released under the terms of the Artistic Licence 2.0
 #
 
-import types
+import six
 import os
 from reclass.errors import InvalidClassnameError
 
 INVALID_CHARACTERS_FOR_CLASSNAMES = ' ' + os.sep
 
+
 class Classes(object):
     '''
     A very limited ordered set of strings with O(n) uniqueness constraints. It
@@ -51,7 +52,7 @@
             self.append_if_new(i)
 
     def _assert_is_string(self, item):
-        if not isinstance(item, types.StringTypes):
+        if not isinstance(item, six.string_types):
             raise TypeError('%s instances can only contain strings, '\
                             'not %s' % (self.__class__.__name__, type(item)))
 
diff --git a/reclass/datatypes/exports.py b/reclass/datatypes/exports.py
index 62ea03f..971befa 100644
--- a/reclass/datatypes/exports.py
+++ b/reclass/datatypes/exports.py
@@ -6,6 +6,8 @@
 
 import copy
 
+from six import iteritems, next
+
 from .parameters import Parameters
 from reclass.errors import ResolveError
 from reclass.values.value import Value
@@ -25,12 +27,12 @@
         self._unrendered.pop(key, None)
 
     def overwrite(self, other):
-        overdict = {'~' + key: value for key, value in other.iteritems()}
+        overdict = {'~' + key: value for (key, value) in iteritems(other)}
         self.merge(overdict)
 
     def interpolate_from_external(self, external):
         while len(self._unrendered) > 0:
-            path, v = self._unrendered.iteritems().next()
+            path, v = next(iteritems(self._unrendered))
             value = path.get_value(self._base)
             if isinstance(value, (Value, ValueList)):
                 external._interpolate_references(path, value, None)
@@ -51,7 +53,7 @@
         required = self._get_required_paths(mainpath)
         while len(required) > 0:
             while len(required) > 0:
-                path, v = required.iteritems().next()
+                path, v = next(iteritems(required))
                 value = path.get_value(self._base)
                 if isinstance(value, (Value, ValueList)):
                     try:
diff --git a/reclass/datatypes/parameters.py b/reclass/datatypes/parameters.py
index ac15925..c96a67d 100644
--- a/reclass/datatypes/parameters.py
+++ b/reclass/datatypes/parameters.py
@@ -10,12 +10,16 @@
 import copy
 import sys
 import types
+
+from six import iteritems, next
+
 from collections import namedtuple
 from reclass.utils.dictpath import DictPath
 from reclass.values.value import Value
 from reclass.values.valuelist import ValueList
 from reclass.errors import InfiniteRecursionError, ResolveError, ResolveErrorList, InterpolationError, ParseError, BadReferencesError
 
+
 class Parameters(object):
     '''
     A class to hold nested dictionaries with the following specialities:
@@ -108,7 +112,7 @@
         return [ self._wrap_value(v, path.new_subpath(k)) for (k, v) in enumerate(source) ]
 
     def _wrap_dict(self, source, path):
-        return { k: self._wrap_value(v, path.new_subpath(k)) for k, v in source.iteritems() }
+        return { k: self._wrap_value(v, path.new_subpath(k)) for (k, v) in iteritems(source) }
 
     def _update_value(self, cur, new):
         if isinstance(cur, Value):
@@ -147,7 +151,7 @@
         """
 
         ret = cur
-        for key, newvalue in new.iteritems():
+        for (key, newvalue) in iteritems(new):
             if key.startswith(self._settings.dict_key_override_prefix) and not self._keep_overrides:
                 ret[key.lstrip(self._settings.dict_key_override_prefix)] = newvalue
             else:
@@ -243,7 +247,7 @@
                     container[key] = value.render(None, None)
 
     def _render_simple_dict(self, dictionary, path):
-        for key, value in dictionary.iteritems():
+        for (key, value) in iteritems(dictionary):
             self._render_simple_container(dictionary, key, value, path)
 
     def _render_simple_list(self, item_list, path):
@@ -256,7 +260,7 @@
             # we could use a view here, but this is simple enough:
             # _interpolate_inner removes references from the refs hash after
             # processing them, so we cannot just iterate the dict
-            path, v = self._unrendered.iteritems().next()
+            path, v = next(iteritems(self._unrendered))
             self._interpolate_inner(path, inventory)
         if self._resolve_errors.have_errors():
             raise self._resolve_errors
diff --git a/reclass/datatypes/tests/test_applications.py b/reclass/datatypes/tests/test_applications.py
index 307a430..6ae07cc 100644
--- a/reclass/datatypes/tests/test_applications.py
+++ b/reclass/datatypes/tests/test_applications.py
@@ -63,7 +63,7 @@
         l = ['a', '~b', 'a', '~d']
         a = Applications(l)
         is_negation = lambda x: x.startswith(a.negation_prefix)
-        GOAL = filter(lambda x: not is_negation(x), set(l)) + filter(is_negation, l)
+        GOAL = list(filter(lambda x: not is_negation(x), set(l))) + list(filter(is_negation, l))
         self.assertEqual('%r' % a, "%s(%r, '~')" % (a.__class__.__name__, GOAL))
 
 if __name__ == '__main__':
diff --git a/reclass/datatypes/tests/test_parameters.py b/reclass/datatypes/tests/test_parameters.py
index 577bdc4..a00f2c6 100644
--- a/reclass/datatypes/tests/test_parameters.py
+++ b/reclass/datatypes/tests/test_parameters.py
@@ -9,6 +9,8 @@
 
 import copy
 
+from six import iteritems
+
 from reclass.settings import Settings
 from reclass.datatypes import Parameters
 from reclass.errors import InfiniteRecursionError, InterpolationError, ResolveError, ResolveErrorList
@@ -132,7 +134,7 @@
         p2, b2 = self._construct_mocked_params(mergee)
         p1.merge(p2)
         p1.initialise_interpolation()
-        for key, value in mergee.iteritems():
+        for (key, value) in iteritems(mergee):
             # check that each key, value in mergee resulted in a get call and
             # a __setitem__ call against b1 (the merge target)
             self.assertIn(mock.call(key), b1.get.call_args_list)
diff --git a/reclass/defaults.py b/reclass/defaults.py
index 980bb92..b245aa8 100644
--- a/reclass/defaults.py
+++ b/reclass/defaults.py
@@ -7,7 +7,7 @@
 # Released under the terms of the Artistic Licence 2.0
 #
 import os, sys
-from version import RECLASS_NAME
+from .version import RECLASS_NAME
 
 # defaults for the command-line options
 OPT_STORAGE_TYPE = 'yaml_fs'
diff --git a/reclass/output/__init__.py b/reclass/output/__init__.py
index 58cd101..42fdb0b 100644
--- a/reclass/output/__init__.py
+++ b/reclass/output/__init__.py
@@ -6,13 +6,15 @@
 # Copyright © 2007–14 martin f. krafft <madduck@madduck.net>
 # Released under the terms of the Artistic Licence 2.0
 #
+
+
 class OutputterBase(object):
 
     def __init__(self):
         pass
 
     def dump(self, data, pretty_print=False):
-        raise NotImplementedError, "dump() method not yet implemented"
+        raise NotImplementedError('dump() method not implemented.')
 
 
 class OutputLoader(object):
@@ -27,6 +29,5 @@
     def load(self, attr='Outputter'):
         klass = getattr(self._module, attr, None)
         if klass is None:
-            raise AttributeError, \
-                'Outputter class {0} does not export "{1}"'.format(self._name, klass)
+            raise AttributeError('Outputter class {0} does not export "{1}"'.format(self._name, klass))
         return klass
diff --git a/reclass/settings.py b/reclass/settings.py
index 44c58d8..e3fc26e 100644
--- a/reclass/settings.py
+++ b/reclass/settings.py
@@ -2,6 +2,11 @@
 import reclass.values.parser_funcs
 from reclass.defaults import *
 
+try:
+    basestring
+except NameError:
+    basestring = str
+
 class Settings(object):
 
     def __init__(self, options={}):
diff --git a/reclass/storage/loader.py b/reclass/storage/loader.py
index 77fdecb..10ca74c 100644
--- a/reclass/storage/loader.py
+++ b/reclass/storage/loader.py
@@ -6,13 +6,15 @@
 # Copyright © 2007–14 martin f. krafft <madduck@madduck.net>
 # Released under the terms of the Artistic Licence 2.0
 #
+import importlib
+
 
 class StorageBackendLoader(object):
 
     def __init__(self, storage_name):
         self._name = 'reclass.storage.' + storage_name
         try:
-            self._module = __import__(self._name, globals(), locals(), self._name)
+            self._module = importlib.import_module(self._name)
         except ImportError:
             raise NotImplementedError
 
@@ -21,7 +23,6 @@
         if klass is None:
             raise AttributeError('Storage backend class {0} does not export '
                                  '"{1}"'.format(self._name, klassname))
-
         return klass
 
     def path_mangler(self, name='path_mangler'):
diff --git a/reclass/storage/memcache_proxy.py b/reclass/storage/memcache_proxy.py
index 405ea8e..8c5e441 100644
--- a/reclass/storage/memcache_proxy.py
+++ b/reclass/storage/memcache_proxy.py
@@ -35,7 +35,7 @@
             return self._real_storage.get_node(name, settings)
         try:
             return self._nodes_cache[name]
-        except KeyError, e:
+        except KeyError as e:
             ret = self._real_storage.get_node(name, settings)
             self._nodes_cache[name] = ret
         return ret
@@ -45,7 +45,7 @@
             return self._real_storage.get_class(name, environment, settings)
         try:
             return self._classes_cache[environment][name]
-        except KeyError, e:
+        except KeyError as e:
             if environment not in self._classes_cache:
                 self._classes_cache[environment] = dict()
             ret = self._real_storage.get_class(name, environment, settings)
diff --git a/reclass/storage/mixed/__init__.py b/reclass/storage/mixed/__init__.py
index 4651e00..990c931 100644
--- a/reclass/storage/mixed/__init__.py
+++ b/reclass/storage/mixed/__init__.py
@@ -6,6 +6,8 @@
 import collections
 import copy
 
+from six import iteritems
+
 import reclass.errors
 from reclass import get_storage
 from reclass.storage import NodeStorageBase
@@ -32,7 +34,7 @@
         self._classes_storage = dict()
         if 'env_overrides' in classes_uri:
             for override in classes_uri['env_overrides']:
-                for env, options in override.iteritems():
+                for (env, options) in iteritems(override):
                         uri = copy.deepcopy(classes_uri)
                         uri.update(options)
                         uri = self._uri(uri)
diff --git a/reclass/storage/yaml_fs/__init__.py b/reclass/storage/yaml_fs/__init__.py
index b92cbfe..83f3666 100644
--- a/reclass/storage/yaml_fs/__init__.py
+++ b/reclass/storage/yaml_fs/__init__.py
@@ -93,7 +93,7 @@
             relpath = self._nodes[name]
             path = os.path.join(self.nodes_uri, relpath)
             name = os.path.splitext(relpath)[0]
-        except KeyError, e:
+        except KeyError as e:
             raise reclass.errors.NodeNotFound(self.name, name, self.nodes_uri)
         entity = YamlData.from_file(path).get_entity(name, settings)
         return entity
@@ -102,7 +102,7 @@
         vvv('GET CLASS {0}'.format(name))
         try:
             path = os.path.join(self.classes_uri, self._classes[name])
-        except KeyError, e:
+        except KeyError as e:
             raise reclass.errors.ClassNotFound(self.name, name, self.classes_uri)
         entity = YamlData.from_file(path).get_entity(name, settings)
         return entity
diff --git a/reclass/storage/yaml_fs/directory.py b/reclass/storage/yaml_fs/directory.py
index 03302b7..614e1c3 100644
--- a/reclass/storage/yaml_fs/directory.py
+++ b/reclass/storage/yaml_fs/directory.py
@@ -7,16 +7,16 @@
 # Released under the terms of the Artistic Licence 2.0
 #
 import os
-import sys
 from reclass.errors import NotFoundError
 
-SKIPDIRS = ( 'CVS', 'SCCS' )
+SKIPDIRS = ('CVS', 'SCCS')
 FILE_EXTENSION = '.yml'
 
 def vvv(msg):
     #print >>sys.stderr, msg
     pass
 
+
 class Directory(object):
 
     def __init__(self, path, fileclass=None):
@@ -39,7 +39,8 @@
     files = property(lambda self: self._files)
 
     def walk(self, register_fn=None):
-        if not callable(register_fn): register_fn = self._register_files
+        if not callable(register_fn):
+            register_fn = self._register_files
 
         def _error(exc):
             raise(exc)
diff --git a/reclass/storage/yaml_git/__init__.py b/reclass/storage/yaml_git/__init__.py
index f4cb287..86c1247 100644
--- a/reclass/storage/yaml_git/__init__.py
+++ b/reclass/storage/yaml_git/__init__.py
@@ -15,6 +15,8 @@
     warnings.simplefilter('ignore')
     import pygit2
 
+from six import iteritems
+
 import reclass.errors
 from reclass.storage import NodeStorageBase
 from reclass.storage.common import NameMangler
@@ -180,7 +182,7 @@
 
     def nodes(self, branch, subdir):
         ret = {}
-        for name, file in self.files[branch].iteritems():
+        for (name, file) in iteritems(self.files[branch]):
             if subdir is None or name.startswith(subdir):
                 node_name = os.path.splitext(file.name)[0]
                 if node_name in ret:
@@ -209,7 +211,7 @@
             self._classes_uri = []
             if 'env_overrides' in classes_uri:
                 for override in classes_uri['env_overrides']:
-                    for env, options in override.iteritems():
+                    for (env, options) in iteritems(override):
                         uri = GitURI(self._classes_default_uri)
                         uri.update({ 'branch': env })
                         uri.update(options)
diff --git a/reclass/storage/yamldata.py b/reclass/storage/yamldata.py
index 0dda2b7..ac3dcb9 100644
--- a/reclass/storage/yamldata.py
+++ b/reclass/storage/yamldata.py
@@ -22,11 +22,10 @@
         if not os.access(abs_path, os.R_OK):
             raise NotFoundError('Cannot open: %s' % abs_path)
         y = cls('yaml_fs://{0}'.format(abs_path))
-        fp = file(abs_path)
-        data = yaml.safe_load(fp)
-        if data is not None:
-            y._data = data
-        fp.close()
+        with open(abs_path) as fp:
+            data = yaml.safe_load(fp)
+            if data is not None:
+                y._data = data
         return y
 
     @classmethod
diff --git a/reclass/utils/dictpath.py b/reclass/utils/dictpath.py
index aec6722..dfb8b32 100644
--- a/reclass/utils/dictpath.py
+++ b/reclass/utils/dictpath.py
@@ -7,7 +7,8 @@
 # Released under the terms of the Artistic Licence 2.0
 #
 
-import types, re
+import six
+import re
 
 class DictPath(object):
     '''
@@ -61,7 +62,7 @@
         else:
             if isinstance(contents, list):
                 self._parts = contents
-            elif isinstance(contents, types.StringTypes):
+            elif isinstance(contents, six.string_types):
                 self._parts = self._split_string(contents)
             elif isinstance(contents, tuple):
                 self._parts = list(contents)
@@ -76,7 +77,7 @@
         return self._delim.join(str(i) for i in self._parts)
 
     def __eq__(self, other):
-        if isinstance(other, types.StringTypes):
+        if isinstance(other, six.string_types):
             other = DictPath(self._delim, other)
 
         return self._parts == other._parts \
diff --git a/reclass/values/compitem.py b/reclass/values/compitem.py
index 2134ea8..765b323 100644
--- a/reclass/values/compitem.py
+++ b/reclass/values/compitem.py
@@ -5,7 +5,7 @@
 #
 
 from reclass.settings import Settings
-from item import Item
+from .item import Item
 
 class CompItem(Item):
 
diff --git a/reclass/values/dictitem.py b/reclass/values/dictitem.py
index d778fe2..555bd8f 100644
--- a/reclass/values/dictitem.py
+++ b/reclass/values/dictitem.py
@@ -5,7 +5,7 @@
 #
 
 from reclass.settings import Settings
-from item import Item
+from .item import Item
 
 class DictItem(Item):
 
diff --git a/reclass/values/invitem.py b/reclass/values/invitem.py
index 84ea39d..970321b 100644
--- a/reclass/values/invitem.py
+++ b/reclass/values/invitem.py
@@ -7,7 +7,9 @@
 import copy
 import pyparsing as pp
 
-from item import Item
+from six import iteritems
+
+from .item import Item
 from reclass.settings import Settings
 from reclass.utils.dictpath import DictPath
 from reclass.errors import ExpressionError, ParseError, ResolveError
@@ -301,7 +303,7 @@
 
     def _value_expression(self, inventory):
         results = {}
-        for node, items in inventory.iteritems():
+        for (node, items) in iteritems(inventory):
             if self._value_path.exists_in(items):
                 results[node] = copy.deepcopy(self._resolve(self._value_path, items))
         return results
@@ -311,14 +313,14 @@
             ExpressionError('Failed to render %s' % str(self), tbFlag=False)
 
         results = {}
-        for node, items in inventory.iteritems():
+        for (node, items) in iteritems(inventory):
             if self._question.value(context, items) and self._value_path.exists_in(items):
                 results[node] = copy.deepcopy(self._resolve(self._value_path, items))
         return results
 
     def _list_test_expression(self, context, inventory):
         results = []
-        for node, items in inventory.iteritems():
+        for (node, items) in iteritems(inventory):
             if self._question.value(context, items):
                 results.append(node)
         return results
diff --git a/reclass/values/listitem.py b/reclass/values/listitem.py
index c7f29d0..1829e32 100644
--- a/reclass/values/listitem.py
+++ b/reclass/values/listitem.py
@@ -4,7 +4,7 @@
 # This file is part of reclass
 #
 
-from item import Item
+from .item import Item
 from reclass.settings import Settings
 
 class ListItem(Item):
diff --git a/reclass/values/parser.py b/reclass/values/parser.py
index bdd881d..a8adcf0 100644
--- a/reclass/values/parser.py
+++ b/reclass/values/parser.py
@@ -6,10 +6,10 @@
 
 import pyparsing as pp
 
-from compitem import CompItem
-from invitem import InvItem
-from refitem import RefItem
-from scaitem import ScaItem
+from .compitem import CompItem
+from .invitem import InvItem
+from .refitem import RefItem
+from .scaitem import ScaItem
 
 from reclass.errors import ParseError
 from reclass.values.parser_funcs import STR, REF, INV
diff --git a/reclass/values/refitem.py b/reclass/values/refitem.py
index 0ae65e6..3e3341c 100644
--- a/reclass/values/refitem.py
+++ b/reclass/values/refitem.py
@@ -4,7 +4,7 @@
 # This file is part of reclass
 #
 
-from item import Item
+from .item import Item
 from reclass.defaults import REFERENCE_SENTINELS
 from reclass.settings import Settings
 from reclass.utils.dictpath import DictPath
diff --git a/reclass/values/scaitem.py b/reclass/values/scaitem.py
index 466d3c9..d446b3c 100644
--- a/reclass/values/scaitem.py
+++ b/reclass/values/scaitem.py
@@ -5,7 +5,7 @@
 #
 
 from reclass.settings import Settings
-from item import Item
+from .item import Item
 
 class ScaItem(Item):
 
diff --git a/reclass/values/value.py b/reclass/values/value.py
index 4ec6051..74ef272 100644
--- a/reclass/values/value.py
+++ b/reclass/values/value.py
@@ -4,10 +4,10 @@
 # This file is part of reclass
 #
 
-from parser import Parser
-from dictitem import DictItem
-from listitem import ListItem
-from scaitem import ScaItem
+from .parser import Parser
+from .dictitem import DictItem
+from .listitem import ListItem
+from .scaitem import ScaItem
 from reclass.errors import InterpolationError
 
 class Value(object):
diff --git a/reclass/values/valuelist.py b/reclass/values/valuelist.py
index 46d8ec7..fc0eaad 100644
--- a/reclass/values/valuelist.py
+++ b/reclass/values/valuelist.py
@@ -4,6 +4,8 @@
 # This file is part of reclass
 #
 
+from __future__ import print_function
+
 import copy
 import sys
 
@@ -98,7 +100,7 @@
                 if self._settings.ignore_overwritten_missing_references and not isinstance(output, (dict, list)) and n != (len(self._values)-1):
                     new = None
                     last_error = e
-                    print >>sys.stderr, "[WARNING] Reference '%s' undefined" % (str(value))
+                    print("[WARNING] Reference '%s' undefined" % str(value), file=sys.stderr)
                 else:
                     raise e
 
diff --git a/requirements.txt b/requirements.txt
index ea72e95..66f0f4b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
 pyparsing
 pyyaml
 pygit2
+six
diff --git a/setup.py b/setup.py
index 2fb77ae..401236e 100644
--- a/setup.py
+++ b/setup.py
@@ -38,7 +38,7 @@
     url = URL,
     packages = find_packages(exclude=['*tests']), #FIXME validate this
     entry_point = { 'console_scripts': console_scripts },
-    install_requires = ['pyparsing', 'pyyaml'],   #FIXME pygit2 (require libffi-dev, libgit2-dev 0.26.x )
+    install_requires = ['pyparsing', 'pyyaml', 'six'], #FIXME pygit2 (require libffi-dev, libgit2-dev 0.26.x )
 
     classifiers=[
         'Development Status :: 4 - Beta',