diff --git a/src/DatabaseLibrary/connection_manager.py b/src/DatabaseLibrary/connection_manager.py
index 87926ab..a384791 100644
--- a/src/DatabaseLibrary/connection_manager.py
+++ b/src/DatabaseLibrary/connection_manager.py
@@ -315,7 +315,7 @@ def _arg_or_config(arg_value, param_name, *, old_param_name=None, mandatory=Fals
         oracle_driver_mode = _arg_or_config(oracle_driver_mode, "oracle_driver_mode", old_param_name="driverMode")
 
         for param_name, param_value in custom_connection_params.items():
-            _arg_or_config(param_value, param_name)
+            custom_connection_params[param_name] = _arg_or_config(param_value, param_name)
         other_config_file_params = config.get_all_available_params()
         if other_config_file_params:
             logger.info(f"Other params from configuration file: {list(other_config_file_params.keys())}")