diff --git a/UNICADOworkflow/src/parameter_study/estimate_input_value_from_configuration_file.py b/UNICADOworkflow/src/parameter_study/estimate_input_value_from_configuration_file.py
index 5acd568cfa5b965548227a6eae333a3fe26e63b9..7bbf6f848c3069206fc6de6fb687292310f4093a 100644
--- a/UNICADOworkflow/src/parameter_study/estimate_input_value_from_configuration_file.py
+++ b/UNICADOworkflow/src/parameter_study/estimate_input_value_from_configuration_file.py
@@ -242,7 +242,7 @@ def estimate_input_value_from_configuration_file(root_of_study_xml_file, input_p
             if study_counter == 1:
                 new_value_of_input = round(float(current_value_of_input) * (1 + float(file_value)), 6)
             else:
-                new_value_of_input = round(reference_value_of_input * (1 + float(file_value)), 6)
+                new_value_of_input = round(float(reference_value_of_input) * (1 + float(file_value)), 6)
         else:
             # check if the first run of current input parameter should be performed
             if study_counter == 1: