diff --git a/CHANGES.rst b/CHANGES.rst
index 3fa2b76b1b..3dfcfc58af 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,3 +1,10 @@
+v34.0.3
+-------
+
+* #947: Loosen restriction on the version of six required,
+  restoring compatibility with environments relying on
+  six 1.6.0 and later.
+
 v34.0.2
 -------
 
diff --git a/setup.py b/setup.py
index 41a8df3bcc..d89adfea96 100755
--- a/setup.py
+++ b/setup.py
@@ -164,7 +164,7 @@ def pypi_link(pkg_filename):
     python_requires='>=2.6,!=3.0.*,!=3.1.*,!=3.2.*',
     install_requires=[
         'packaging>=16.8',
-        'six>=1.10.0',
+        'six>=1.6.0',
         'appdirs>=1.4.0',
     ],
     extras_require={