diff --git a/source/java/org/alfresco/repo/forum/CommentServiceImpl.java b/source/java/org/alfresco/repo/forum/CommentServiceImpl.java
index b7ae4fd6cf..78a1a67ca9 100644
--- a/source/java/org/alfresco/repo/forum/CommentServiceImpl.java
+++ b/source/java/org/alfresco/repo/forum/CommentServiceImpl.java
@@ -63,7 +63,7 @@ public class CommentServiceImpl implements CommentService
         
         NodeRef result = null;
         for (ChildAssociationRef parentAssoc = nodeService.getPrimaryParent(descendantNodeRef);
-             parentAssoc != null;
+             parentAssoc != null && parentAssoc.getParentRef() != null;
              parentAssoc = nodeService.getPrimaryParent(parentAssoc.getParentRef()))
         {
             if (nodeService.hasAspect(parentAssoc.getParentRef(), ForumModel.ASPECT_DISCUSSABLE))