diff --git a/plone/app/discussion/browser/comments.pt b/plone/app/discussion/browser/comments.pt
index 34c82ab..4f88c6b 100644
--- a/plone/app/discussion/browser/comments.pt
+++ b/plone/app/discussion/browser/comments.pt
@@ -29,21 +29,22 @@
                  tal:define="reply reply_dict/comment;
                              depth reply_dict/depth|python:0;
                              creator reply/Creator;
-                             author_home_url string:${context/portal_url}/author/${reply/author_username};
-                             portrait python:here.portal_membership.getPersonalPortrait(reply.author_username);
+                             author_home_url python:view.get_commenter_home_url(username=reply.author_username);
+                             portrait_url python:view.get_commenter_portrait(reply.author_username);
                              anonymous_creator python:creator in ('Anonymous User', '');"
                  tal:attributes="class python:'comment replyTreeLevel'+str(depth);
                                  style string:margin-left: ${depth}em;
                                  id string:comment-${reply/id}">
 
                 <div class="commentImage" tal:condition="showCommenterImage">
+
                     <a href="" tal:condition="not:isAnon"
                                tal:attributes="href author_home_url">
                          <img src="defaultUser.gif"
                               alt=""
                               border="0"
                               width="75"
-                              tal:attributes="src portrait/absolute_url;
+                              tal:attributes="src portrait_url;
                                               alt reply/creator" />
                     </a>
                     <img src="defaultUser.gif"
@@ -51,7 +52,7 @@
                          border="0"
                          width="75"
                          tal:condition="isAnon"
-                         tal:attributes="src portrait/absolute_url;
+                         tal:attributes="src portrait_url;
                                          alt reply/creator" />
                 </div>
 
diff --git a/plone/app/discussion/browser/comments.py b/plone/app/discussion/browser/comments.py
index 078d0b2..9f333eb 100644
--- a/plone/app/discussion/browser/comments.py
+++ b/plone/app/discussion/browser/comments.py
@@ -100,9 +100,11 @@ class CommentsViewlet(ViewletBase):
     def get_commenter_portrait(self, username):
 
         if username is None:
-            return None
+            # return the default user image if no username is given
+            return 'defaultUser.gif'
         else:
-            return self.portal_membership.getPersonalPortrait(username);
+            portal_membership = getToolByName(self.context, 'portal_membership', None)
+            return portal_membership.getPersonalPortrait(username).absolute_url();
 
     def anonymous_discussion_allowed(self):
         # Check if anonymous comments are allowed in the registry