diff --git a/tcp_tests/helpers/env_config.py b/tcp_tests/helpers/env_config.py
index b811030..ef07866 100644
--- a/tcp_tests/helpers/env_config.py
+++ b/tcp_tests/helpers/env_config.py
@@ -223,7 +223,7 @@
     elif i_count > 0 and not isinstance(data[key], list):
         raise TypeError(
             ("Key '{0}' by '{1}' keypath expected as list "
-             "but '{3}' obj found").format(
+             "but '{2}' obj found").format(
                  key, keypath(walked_paths), type(data[key]).__name__
             )
         )