diff --git a/GANDLF/config_manager.py b/GANDLF/config_manager.py
index 44f7da6de..3f916ec5a 100644
--- a/GANDLF/config_manager.py
+++ b/GANDLF/config_manager.py
@@ -651,7 +651,7 @@ def _parseConfig(
         parallel_compute_command = parallel_compute_command.replace('"', "")
     params["parallel_compute_command"] = parallel_compute_command
 
-    if params["opt"] is not None:
+    if "opt" in params:
         print("DeprecationWarning: 'opt' has been superseded by 'optimizer'")
         params["optimizer"] = params["opt"]