diff --git a/korman/exporter/manager.py b/korman/exporter/manager.py
index 06c4360..6ff74b3 100644
--- a/korman/exporter/manager.py
+++ b/korman/exporter/manager.py
@@ -90,6 +90,7 @@ class ExportManager:
                     name = bl.name
                 else:
                     name = so.key.name
+            assert issubclass(pl, hsKeyedObject)
             pl = pl(name)
 
         self.AddObject(location, pl)