diff --git a/libs/langchain/langchain/smith/evaluation/config.py b/libs/langchain/langchain/smith/evaluation/config.py
index 9348e2d81cb..3f8224d7c18 100644
--- a/libs/langchain/langchain/smith/evaluation/config.py
+++ b/libs/langchain/langchain/smith/evaluation/config.py
@@ -48,6 +48,8 @@ class EvalConfig(BaseModel):
         for field, val in self:
             if field == "evaluator_type":
                 continue
+            elif val is None:
+                continue
             kwargs[field] = val
         return kwargs