diff --git a/plone/app/discussion/catalog.py b/plone/app/discussion/catalog.py
index 03441c4..31fdcbd 100644
--- a/plone/app/discussion/catalog.py
+++ b/plone/app/discussion/catalog.py
@@ -16,6 +16,11 @@ from plone.app.discussion.interfaces import IConversation, IComment
 
 from plone.indexer import indexer
 
+try:
+    from plone.uuid.interfaces import IUUID
+except ImportError:
+    IUUID = None
+
 MAX_DESCRIPTION = 25
 
 # Conversation Indexers
@@ -130,3 +135,9 @@ def comments_last_comment_date(object):
 @indexer(IComment)
 def comments_commentators(object):
     return None
+
+# Make sure comments don't inherit their container's UID
+@indexer(IComment)
+def UID(object):
+    if IUUID:
+        return IUUID(object, None)
diff --git a/plone/app/discussion/configure.zcml b/plone/app/discussion/configure.zcml
index f72c5c9..a3afbca 100644
--- a/plone/app/discussion/configure.zcml
+++ b/plone/app/discussion/configure.zcml
@@ -101,6 +101,7 @@
     <adapter name="in_response_to" factory=".catalog.in_response_to" />
 
     <!-- Comment indexes -->
+    <adapter name="UID" factory=".catalog.UID" />
     <adapter name="Title" factory=".catalog.title" />
     <adapter name="Creator" factory=".catalog.creator" />
     <adapter name="Description" factory=".catalog.description" />
diff --git a/plone/app/discussion/tests/test_comment.py b/plone/app/discussion/tests/test_comment.py
index 52cc63b..bd0b164 100644
--- a/plone/app/discussion/tests/test_comment.py
+++ b/plone/app/discussion/tests/test_comment.py
@@ -71,27 +71,36 @@ class CommentTest(PloneTestCase):
         conversation.addComment(comment1)
         comment_brain = self.catalog.searchResults(
                             portal_type = 'Discussion Item')[0]
-        self.failUnless(comment_brain.UID)
+        
+        # comment should only have a UID if plone.uuid is present
+        try:
+            from plone.uuid.interfaces import IUUID
+            IUUID # pyflakes
+        except ImportError:
+            self.failIf(comment_brain.UID)
+        else:
+            self.failUnless(comment_brain.UID)
         
     def test_uid_is_unique(self):
-        conversation = IConversation(self.portal.doc1)        
+        conversation = IConversation(self.portal.doc1)
         comment1 = createObject('plone.Comment')
         conversation.addComment(comment1)
         comment2 = createObject('plone.Comment')
         conversation.addComment(comment2)
         brains = self.catalog.searchResults(
                      portal_type = 'Discussion Item')
-        self.assertNotEquals(brains[0].UID, None)
-        self.assertNotEquals(brains[1].UID, None)
-        self.assertNotEquals(brains[0].UID, brains[1].UID)
+        
+        # make sure uids are either both None (i.e. without plone.uuid),
+        # or not equal
+        if brains[0].UID != None or brains[1].UID != None:
+            self.assertNotEquals(brains[0].UID, brains[1].UID)
     
     def test_comment_uid_differs_from_content_uid(self):
-        conversation = IConversation(self.portal.doc1)        
+        conversation = IConversation(self.portal.doc1)
         comment1 = createObject('plone.Comment')
         conversation.addComment(comment1)
         comment_brain = self.catalog.searchResults(
                             portal_type = 'Discussion Item')[0]
-        self.assertNotEquals(comment_brain.UID, None)
         self.assertNotEquals(self.document_brain.UID, comment_brain.UID)
 
     def test_title(self):
diff --git a/setup.py b/setup.py
index 7459942..43c5255 100644
--- a/setup.py
+++ b/setup.py
@@ -1,7 +1,33 @@
+import sys
 from setuptools import setup, find_packages
 
 version = '1.0bRC1'
 
+install_requires = [
+    'setuptools',
+    'collective.autopermission',
+    'collective.monkeypatcher',
+    'plone.app.layout',
+    'plone.app.registry',
+    'plone.app.z3cform',
+    'plone.indexer',
+    'plone.registry',
+    'plone.z3cform',
+    'ZODB3',
+    'zope.interface',
+    'zope.component',
+    'zope.annotation',
+    'zope.event',
+    'zope.container',
+    'zope.lifecycleevent',
+    'zope.site',
+    'z3c.form>=2.3.3',
+    ]
+
+# On Python 2.6 (implying Plone 4), require plone.app.uuid
+if sys.version_info >= (2,6):
+    install_requires.append('plone.app.uuid')
+
 setup(name='plone.app.discussion',
       version=version,
       description="Enhanced discussion support for Plone",
@@ -20,27 +46,7 @@ setup(name='plone.app.discussion',
       namespace_packages=['plone', 'plone.app'],
       include_package_data=True,
       zip_safe=False,
-      install_requires=[
-          'setuptools',
-          'collective.autopermission',
-          'collective.monkeypatcher',
-          'plone.app.layout',
-          'plone.app.registry',
-          'plone.app.uuid',          
-          'plone.app.z3cform',
-          'plone.indexer',
-          'plone.registry',
-          'plone.z3cform',
-          'ZODB3',
-          'zope.interface',
-          'zope.component',
-          'zope.annotation',
-          'zope.event',
-          'zope.container',
-          'zope.lifecycleevent',
-          'zope.site',
-          'z3c.form>=2.3.3',
-      ],
+      install_requires=install_requires,
       extras_require = {
           'test': [
               'plone.app.testing',