diff --git a/flask/sessions.py b/flask/sessions.py
index 04b7f8af..0b35b1c2 100644
--- a/flask/sessions.py
+++ b/flask/sessions.py
@@ -15,9 +15,9 @@ from datetime import datetime
 from werkzeug.http import http_date, parse_date
 from werkzeug.datastructures import CallbackDict
 from . import Markup, json
+from ._compat import iteritems, text_type
 
 from itsdangerous import URLSafeTimedSerializer, BadSignature
-import six
 
 
 def total_seconds(td):
@@ -63,16 +63,16 @@ class TaggedJSONSerializer(object):
             elif isinstance(value, uuid.UUID):
                 return {' u': value.hex}
             elif callable(getattr(value, '__html__', None)):
-                return {' m': six.text_type(value.__html__())}
+                return {' m': text_type(value.__html__())}
             elif isinstance(value, list):
                 return [_tag(x) for x in value]
             elif isinstance(value, datetime):
                 return {' d': http_date(value)}
             elif isinstance(value, dict):
-                return dict((k, _tag(v)) for k, v in six.iteritems(value))
+                return dict((k, _tag(v)) for k, v in iteritems(value))
             elif isinstance(value, str):
                 try:
-                    return six.text_type(value)
+                    return text_type(value)
                 except UnicodeError:
                     raise UnexpectedUnicodeError(u'A byte string with '
                         u'non-ASCII data was passed to the session system '
@@ -85,7 +85,7 @@ class TaggedJSONSerializer(object):
         def object_hook(obj):
             if len(obj) != 1:
                 return obj
-            the_key, the_value = six.advance_iterator(obj.iteritems())
+            the_key, the_value = next(iteritems(obj))
             if the_key == ' t':
                 return tuple(the_value)
             elif the_key == ' u':