diff --git a/openai/validators.py b/openai/validators.py
index 078179a44b..b7f6364084 100644
--- a/openai/validators.py
+++ b/openai/validators.py
@@ -423,7 +423,7 @@ def completions_space_start_validator(df):
 
     def add_space_start(x):
         x["completion"] = x["completion"].apply(
-            lambda x: ("" if x[0] == " " else " ") + x
+            lambda s: ("" if s.startswith(" ") else " ") + s
         )
         return x