diff --git a/tools/python/jwutils/Config.py b/tools/python/jwutils/Config.py
index e7dd364..e8f456d 100644
--- a/tools/python/jwutils/Config.py
+++ b/tools/python/jwutils/Config.py
@@ -107,7 +107,10 @@ class Config(): # export
         self.__conf.dump(DEBUG, "superposed configuration")
 
     def __getitem__(self, key: str) -> Optional[str]:
-        return self.get(key)
+        ret = self.get(key)
+        if ret is None:
+            raise KeyError(key)
+        return ret
 
     def __setitem__(self, key: str, value: str):
         return self.set(key, value)