--- a/Allura/allura/model/discuss.py
+++ b/Allura/allura/model/discuss.py
@@ -503,7 +503,8 @@
             self.thread.last_post_date,
             self.mod_date)
         self.thread.update_stats()
-        artifact.update_stats()
+        if hasattr(artifact, 'update_stats'):
+            artifact.update_stats()
         g.director.create_activity(author, 'posted', self, target=artifact,
                 related_nodes=[self.app_config.project])