diff --git a/guardrails/classes/schema/model_schema.py b/guardrails/classes/schema/model_schema.py
index cb28770ee..f2c1c3266 100644
--- a/guardrails/classes/schema/model_schema.py
+++ b/guardrails/classes/schema/model_schema.py
@@ -6,6 +6,8 @@
 class ModelSchema(IModelSchema):
     def to_dict(self) -> Dict[str, Any]:
         super_dict = super().to_dict()
+        if not super_dict:
+            return super_dict
         return {k: v for k, v in super_dict.items() if v is not None}
 
     @classmethod