diff -up matplotlib-1.5.1/setupext.py.six matplotlib-1.5.1/setupext.py
--- matplotlib-1.5.1/setupext.py.six	2016-01-10 23:20:20.000000000 +0100
+++ matplotlib-1.5.1/setupext.py	2016-05-18 13:44:21.534494158 +0200
@@ -1026,6 +1026,18 @@ class Qhull(SetupPackage):
             ext.sources.extend(glob.glob('extern/qhull/*.c'))
 
 
+class Six(SetupPackage):
+    name = "six"
+
+    def check(self):
+        try:
+            import six
+        except ImportError:
+            return 'not found. pip may install it below.'
+
+        return 'version %s' % six.__version__
+
+
 class TTConv(SetupPackage):
     name = "ttconv"
 
diff -up matplotlib-1.5.1/setup.py.six matplotlib-1.5.1/setup.py
--- matplotlib-1.5.1/setup.py.six	2016-01-10 23:20:20.000000000 +0100
+++ matplotlib-1.5.1/setup.py	2016-05-18 13:44:21.528494040 +0200
@@ -84,7 +84,7 @@ mpl_packages = [
     setupext.Delaunay(),
     setupext.QhullWrap(),
     setupext.Tri(),
-    setupext.Externals(),
+    setupext.Six(),
     'Optional subpackages',
     setupext.SampleData(),
     setupext.Toolkits(),