diff --git a/plone/app/discussion/catalog.py b/plone/app/discussion/catalog.py
index 894d719..e87af0b 100644
--- a/plone/app/discussion/catalog.py
+++ b/plone/app/discussion/catalog.py
@@ -72,7 +72,7 @@ def title(object):
 
 @indexer(IComment)
 def creator(object):
-    return object.creator and safe_unicode(object.creator)
+    return object.creator and safe_unicode(object.creator).encode('utf-8')
 
 @indexer(IComment)
 def description(object):