diff --git a/plone/app/discussion/browser/comments.py b/plone/app/discussion/browser/comments.py
index b0cfb39..4521a6d 100644
--- a/plone/app/discussion/browser/comments.py
+++ b/plone/app/discussion/browser/comments.py
@@ -17,6 +17,7 @@ from plone.z3cform import z2
 from plone.z3cform.fieldsets import extensible
 from plone.z3cform.interfaces import IWrappedForm
 from Products.CMFCore.utils import getToolByName
+from Products.CMFPlone.utils import safe_unicode
 from Products.Five.browser.pagetemplatefile import ViewPageTemplateFile
 from Products.statusmessages.interfaces import IStatusMessage
 from six.moves.urllib.parse import quote
@@ -152,13 +153,9 @@ class CommentForm(extensible.ExtensibleForm, form.Form):
 
         # Make sure author_name/ author_email is properly encoded
         if 'author_name' in data:
-            author_name = data['author_name']
-            if isinstance(author_name, str):
-                author_name = six.text_type(author_name, 'utf-8')
+            author_name = safe_unicode(data['author_name'])
         if 'author_email' in data:
-            author_email = data['author_email']
-            if isinstance(author_email, str):
-                author_email = six.text_type(author_email, 'utf-8')
+            author_email = safe_unicode(data['author_email'])
 
         # Set comment author properties for anonymous users or members
         portal_membership = getToolByName(context, 'portal_membership')
@@ -167,8 +164,7 @@ class CommentForm(extensible.ExtensibleForm, form.Form):
                 'Reply to item', context):
             # Member
             member = portal_membership.getAuthenticatedMember()
-            # memberdata is stored as utf-8 encoded strings
-            email = member.getProperty('email')
+            email = safe_unicode(member.getProperty('email'))
             fullname = member.getProperty('fullname')
             if not fullname or fullname == '':
                 fullname = member.getUserName()
diff --git a/plone/app/discussion/conversation.py b/plone/app/discussion/conversation.py
index 5a6ed71..ae13301 100644
--- a/plone/app/discussion/conversation.py
+++ b/plone/app/discussion/conversation.py
@@ -347,20 +347,20 @@ class ConversationReplies(object):
         return len(self.children)
 
     def __contains__(self, key):
-        return long(key) in self.children
+        return int(key) in self.children
 
     def __getitem__(self, key):
-        """Get an item by its long key
+        """Get an item by its int key
         """
-        key = long(key)
+        key = int(key)
         if key not in self.children:
             raise KeyError(key)
         return self.conversation[key]
 
     def __delitem__(self, key):
-        """Delete an item by its long key
+        """Delete an item by its int key
         """
-        key = long(key)
+        key = int(key)
         if key not in self.children:
             raise KeyError(key)
         del self.conversation[key]
@@ -369,7 +369,7 @@ class ConversationReplies(object):
         return iter(self.children)
 
     def get(self, key, default=None):
-        key = long(key)
+        key = int(key)
         if key not in self.children:
             return default
         return self.conversation.get(key)
diff --git a/plone/app/discussion/tests/functional_test_comments.txt b/plone/app/discussion/tests/functional_test_comments.txt
index d78a7eb..36ad8a1 100644
--- a/plone/app/discussion/tests/functional_test_comments.txt
+++ b/plone/app/discussion/tests/functional_test_comments.txt
@@ -470,7 +470,7 @@ Edit the content object.
     >>> from hashlib import sha1 as sha
     >>> ring = _getKeyring('foo')
     >>> secret = ring.random()
-    >>> token = hmac.new(secret, 'admin', sha).hexdigest()
+    >>> token = hmac.new(secret.encode('utf8'), b'admin', sha).hexdigest()
     >>> browser.open("http://nohost/plone/doc1/edit?_authenticator=" + token)
     >>> browser.getControl(name='form.widgets.IRichTextBehavior.text').value = "Lorem ipsum"
     >>> browser.getControl('Save').click()
diff --git a/plone/app/discussion/tests/test_comment.py b/plone/app/discussion/tests/test_comment.py
index 8ac4d93..0600986 100644
--- a/plone/app/discussion/tests/test_comment.py
+++ b/plone/app/discussion/tests/test_comment.py
@@ -171,9 +171,10 @@ class CommentTest(unittest.TestCase):
     def test_getText_with_non_ascii_characters(self):
         comment1 = createObject('plone.Comment')
         comment1.text = u'Umlaute sind ä, ö und ü.'
+        out = b'<p>Umlaute sind \xc3\xa4, \xc3\xb6 und \xc3\xbc.</p>'
         self.assertEqual(
             comment1.getText(),
-            '<p>Umlaute sind \xc3\xa4, \xc3\xb6 und \xc3\xbc.</p>',
+            out.decode('utf8')
         )
 
     def test_getText_doesnt_link(self):
diff --git a/plone/app/discussion/tests/test_comments_viewlet.py b/plone/app/discussion/tests/test_comments_viewlet.py
index 5a34cb6..942f0d2 100644
--- a/plone/app/discussion/tests/test_comments_viewlet.py
+++ b/plone/app/discussion/tests/test_comments_viewlet.py
@@ -567,7 +567,8 @@ class TestCommentsViewlet(unittest.TestCase):
         replies = self.viewlet.get_replies()
         next(replies)
         next(replies)
-        self.assertRaises(StopIteration, replies.next)
+        with self.assertRaises(StopIteration):
+            next(replies)
 
     def test_get_replies_on_non_annotatable_object(self):
         context = self.portal.MailHost      # the mail host is not annotatable
@@ -575,7 +576,8 @@ class TestCommentsViewlet(unittest.TestCase):
         replies = viewlet.get_replies()
         self.assertEqual(len(tuple(replies)), 0)
         replies = viewlet.get_replies()
-        self.assertRaises(StopIteration, replies.next)
+        with self.assertRaises(StopIteration):
+            next(replies)
 
     def test_get_replies_with_workflow_actions(self):
         self.assertFalse(self.viewlet.get_replies(workflow_actions=True))
diff --git a/plone/app/discussion/tests/test_contentrules.py b/plone/app/discussion/tests/test_contentrules.py
index 6b9610e..c05aede 100644
--- a/plone/app/discussion/tests/test_contentrules.py
+++ b/plone/app/discussion/tests/test_contentrules.py
@@ -54,7 +54,7 @@ class CommentContentRulesTest(unittest.TestCase):
     def testCommentIdStringSubstitution(self):
         comment_id = getAdapter(self.document, IStringSubstitution,
                                 name=u'comment_id')
-        self.assertIsInstance(comment_id(), long)
+        self.assertIsInstance(comment_id(), int)
 
     def testCommentTextStringSubstitution(self):
         comment_text = getAdapter(self.document, IStringSubstitution,
@@ -114,7 +114,7 @@ class ReplyContentRulesTest(unittest.TestCase):
             IStringSubstitution,
             name=u'comment_id',
         )
-        self.assertIsInstance(reply_id(), long)
+        self.assertIsInstance(reply_id(), int)
 
     def testReplyTextStringSubstitution(self):
         reply_text = getAdapter(
diff --git a/plone/app/discussion/tests/test_conversation.py b/plone/app/discussion/tests/test_conversation.py
index 6f94894..fcf528c 100644
--- a/plone/app/discussion/tests/test_conversation.py
+++ b/plone/app/discussion/tests/test_conversation.py
@@ -68,7 +68,7 @@ class ConversationTest(unittest.TestCase):
         new_id = conversation.addComment(comment)
 
         # Check that the conversation methods return the correct data
-        self.assertTrue(isinstance(comment.comment_id, long))
+        self.assertTrue(isinstance(comment.comment_id, int))
         self.assertTrue(IComment.providedBy(conversation[new_id]))
         self.assertEqual(
             aq_base(conversation[new_id].__parent__),
@@ -641,7 +641,7 @@ class ConversationTest(unittest.TestCase):
 
     def test_unconvertible_id(self):
         # make sure the conversation view doesn't break when given comment id
-        # can't be converted to long
+        # can't be converted to int
 
         conversation = self.portal.doc1.restrictedTraverse(
             '++conversation++default/ThisCantBeRight',