--- a/openid_cla/cla.py
+++ b/openid_cla/cla.py
@@ -9,7 +9,6 @@
 from openid.extension import Extension
 import logging
 
-import six
 
 __all__ = [
     'CLARequest',
@@ -88,7 +87,7 @@
             self.requested.append(cla_uri)
 
     def requestCLAs(self, cla_uris):
-        if isinstance(cla_uris, six.string_types):
+        if isinstance(cla_uris, str):
             raise TypeError('CLA URIs should be passed as a list of '
                             'strings (not %r)' % (type(field_names),))
 
--- a/setup.py
+++ b/setup.py
@@ -26,7 +26,7 @@
 import sys
 from setuptools import setup, find_packages
 
-install_requires = ['six']
+install_requires = []
 
 if sys.version_info[0] == 2:
     install_requires.append('python-openid>=2.2.5')