diff --git a/src/cohere/core/pydantic_utilities.py b/src/cohere/core/pydantic_utilities.py
index 0f24b0ea8..f02a5e0e4 100644
--- a/src/cohere/core/pydantic_utilities.py
+++ b/src/cohere/core/pydantic_utilities.py
@@ -84,9 +84,11 @@ def to_jsonable_with_fallback(
 
 class UniversalBaseModel(pydantic.BaseModel):
     class Config:
-        populate_by_name = True
-        smart_union = True
-        allow_population_by_field_name = True
+        if IS_PYDANTIC_V2:
+            populate_by_name = True
+        else:
+            smart_union = True
+            allow_population_by_field_name = True
         json_encoders = {dt.datetime: serialize_datetime}
 
     def json(self, **kwargs: typing.Any) -> str: