diff --git a/src/App/tests/testImageFile.py b/src/App/tests/testImageFile.py
index 954c1c8edb..0783783fe4 100644
--- a/src/App/tests/testImageFile.py
+++ b/src/App/tests/testImageFile.py
@@ -63,7 +63,7 @@ def test_index_html(self):
                             'www', 'zopelogo.png')
         image = App.ImageFile.ImageFile(path)
         result = image.index_html(request, response)
-        self.assertEqual(stdout.getvalue(), '')
+        self.assertEqual(stdout.getvalue(), b'')
         self.assertTrue(isinstance(result, io.FileIO))
         self.assertTrue(b''.join(result).startswith(b'\x89PNG\r\n'))
         self.assertEqual(len(result), image.size)
diff --git a/src/Products/Five/browser/decode.py b/src/Products/Five/browser/decode.py
index 960c7c93de..a44081b220 100644
--- a/src/Products/Five/browser/decode.py
+++ b/src/Products/Five/browser/decode.py
@@ -21,8 +21,7 @@
 from ZPublisher.HTTPRequest import isCGI_NAMEs
 from zope.i18n.interfaces import IUserPreferredCharsets
 
-if sys.version_info >= (3, ):
-    unicode = str
+from six import text_type, binary_type
 
 
 def _decode(text, charsets):
@@ -31,7 +30,7 @@ def _decode(text, charsets):
     # taken and adapted from zope.publisher.browser.BrowserRequest
     for charset in charsets:
         try:
-            text = unicode(text, charset)
+            text = text_type(text, charset)
             break
         except UnicodeError:
             pass
@@ -54,16 +53,16 @@ def processInputValue(value, charsets):
         for k, v in list(value.items()):
             value[k] = processInputValue(v, charsets)
         return value
-    elif isinstance(value, str):
+    elif isinstance(value, binary_type):
         return _decode(value, charsets)
     else:
         return value
 
 
 def processInputs(request, charsets=None):
-    """Process the values in request.form to decode strings to unicode, using
-    the passed-in list of charsets. If none are passed in, look up the user's
-    preferred charsets. The default is to use utf-8.
+    """Process the values in request.form to decode binary_type to text_type,
+    using the passed-in list of charsets. If none are passed in, look up the
+    user's preferred charsets. The default is to use utf-8.
     """
     warn(u'processInputs() is deprecated and will be removed in Zope 5.0. If '
          u'your view implements IBrowserPage, similar processing is now '
diff --git a/src/Products/Five/tests/test_i18n.py b/src/Products/Five/tests/test_i18n.py
index 55811f30a2..0a27bf240b 100644
--- a/src/Products/Five/tests/test_i18n.py
+++ b/src/Products/Five/tests/test_i18n.py
@@ -46,10 +46,10 @@ def test_directive():
     As you can see, both the default functionality and translation to
     German work:
 
-      >>> translate(msg)
-      u'This is an explicit message'
-      >>> translate(msg, target_language='de')
-      u'Dies ist eine explizite Nachricht'
+      >>> translate(msg) == u'This is an explicit message'
+      True
+      >>> translate(msg, target_language='de') == u'Dies ist eine explizite Nachricht'
+      True
     """
 
 
diff --git a/src/Products/Five/utilities/marker.py b/src/Products/Five/utilities/marker.py
index da7c2a88ce..aa8ab3bd26 100644
--- a/src/Products/Five/utilities/marker.py
+++ b/src/Products/Five/utilities/marker.py
@@ -16,8 +16,6 @@
 Allows for arbitrary application of marker interfaces to objects.
 """
 
-from sets import Set
-
 from zope.interface import implementer, implementedBy, providedBy
 from zope.interface import directlyProvides, directlyProvidedBy
 from zope.interface.interfaces import IInterface
@@ -105,12 +103,12 @@ def update(self, add=(), remove=()):
         marker_ifaces = self.getAvailableInterfaces()
         if len(add):
             [mark(self.context, interface)
-             for interface in Set(marker_ifaces) & Set(add)]
+             for interface in set(marker_ifaces) & set(add)]
 
         direct_ifaces = self.getDirectlyProvided()
         if len(remove):
             [erase(self.context, interface)
-             for interface in Set(direct_ifaces) & Set(remove)]
+             for interface in set(direct_ifaces) & set(remove)]
 
     def _getInterfaceNames(self, interfaces):
         return [interfaceToName(self, iface) for iface in interfaces]
diff --git a/src/Testing/ZopeTestCase/zopedoctest/functional.py b/src/Testing/ZopeTestCase/zopedoctest/functional.py
index 20fb1bfb8e..a2b7c79d6e 100644
--- a/src/Testing/ZopeTestCase/zopedoctest/functional.py
+++ b/src/Testing/ZopeTestCase/zopedoctest/functional.py
@@ -305,8 +305,8 @@ def setup_globs(self):
         globs['http'] = http
         globs['getRootFolder'] = getRootFolder
         globs['sync'] = sync
-        globs['user_auth'] = base64.encodestring(
-            '%s:%s' % (user_name, user_password))
+        unencoded_user_auth = ('%s:%s' % (user_name, user_password)).encode('utf-8')
+        globs['user_auth'] = base64.encodestring(unencoded_user_auth)
 
     def setup_test_class(self):
         test_class = self._kw.get('test_class', FunctionalTestCase)