diff --git a/scripts/Diffraction/isis_powder/polaris_routines/polaris_param_mapping.py b/scripts/Diffraction/isis_powder/polaris_routines/polaris_param_mapping.py
index 8a9f354ef2d8bc47052dec22942178d89667f061..53b5d8de3b97d6a7f562939f3ba7fe6e08e8d131 100644
--- a/scripts/Diffraction/isis_powder/polaris_routines/polaris_param_mapping.py
+++ b/scripts/Diffraction/isis_powder/polaris_routines/polaris_param_mapping.py
@@ -20,7 +20,7 @@ attr_mapping = \
      ParamMapEntry(ext_name="input_mode",                  int_name="input_mode", enum_class=INPUT_BATCHING),
      ParamMapEntry(ext_name="merge_banks",                 int_name="merge_banks"),
      ParamMapEntry(ext_name="mode",                        int_name="mode", enum_class=POLARIS_CHOPPER_MODES),
-     ParamMapEntry(ext_name="multiple_scattering",         int_name="multiple_scattering"),
+     ParamMapEntry(ext_name="multiple_scattering",         int_name="multiple_scattering", optional=True),
      ParamMapEntry(ext_name="raw_data_cropping_values",    int_name="raw_data_crop_values"),
      ParamMapEntry(ext_name="run_number",                  int_name="run_number"),
      ParamMapEntry(ext_name="sample_empty",                int_name="sample_empty",   optional=True),