diff --git a/image_prediction/formatter/formatters/camel_case.py b/image_prediction/formatter/formatters/camel_case.py
index bb6cd9d..a91a727 100644
--- a/image_prediction/formatter/formatters/camel_case.py
+++ b/image_prediction/formatter/formatters/camel_case.py
@@ -10,7 +10,7 @@ class Snake2CamelCaseKeyFormatter(Formatter):
 
         if isinstance(key, str):
             head, *tail = key.split("_")
-            return head + "".join(map(lambda s: s.title(), tail))
+            return head + "".join(map(str.title, tail))
         else:
             return key