diff --git a/jambo/schema_converter.py b/jambo/schema_converter.py
index 00819b4..302b190 100644
--- a/jambo/schema_converter.py
+++ b/jambo/schema_converter.py
@@ -66,7 +66,7 @@ class SchemaConverter:
             :return: The generated Pydantic model.
         """
         if ref_cache is None:
-            ref_cache: RefCacheDict = dict()
+            ref_cache = dict()
 
         try:
             validator = validator_for(schema)