diff --git a/ait/core/util.py b/ait/core/util.py
index 24ec9979..e8c79c37 100755
--- a/ait/core/util.py
+++ b/ait/core/util.py
@@ -157,7 +157,7 @@ def create(*args, **kwargs):
 
     extensions = ait.config.get('extensions', None)
 
-    for clsname, cls in modsyms.items():
+    for clsname, cls in modsyms.copy().items():
         if not isinstance(cls, type):
             continue