--- a/Allura/allura/model/session.py
+++ b/Allura/allura/model/session.py
@@ -64,10 +64,12 @@
             for obj in self.objects_added:
                 ArtifactReference.from_artifact(obj)
             # Post delete and add indexing operations
-            allura.tasks.index_tasks.del_artifacts.post(
-                [ obj.index_id() for obj in self.objects_deleted ])
-            allura.tasks.index_tasks.add_artifacts.post(
-                [ obj.index_id() for obj in self.objects_added + self.objects_modified ])
+            if self.objects_deleted:
+                allura.tasks.index_tasks.del_artifacts.post(
+                    [ obj.index_id() for obj in self.objects_deleted ])
+            if self.objects_added or self.objects_modified:
+                allura.tasks.index_tasks.add_artifacts.post(
+                    [ obj.index_id() for obj in self.objects_added + self.objects_modified ])
             # Flush tasks
             main_orm_session.flush()
             for obj in self.objects_added: