diff --git a/etl/customers/newhaven/newhaven_study.py b/etl/customers/newhaven/newhaven_study.py
index b10a8bf0..ab601fdc 100644
--- a/etl/customers/newhaven/newhaven_study.py
+++ b/etl/customers/newhaven/newhaven_study.py
@@ -104,9 +104,9 @@ def make_asset_list():
         if address_base_property_description == "Self Contained Flat (Includes Maisonette / Apartment)":
             if epc_property_type == "Flat":
                 return 1
-            if epc_property_type == "House":
+            if epc_property_type == "Maisonette":
                 return 2
-            return NotImplementedError("Implement me")
+            raise NotImplementedError("Implement me")
 
         if pd.isnull(floor_height):
             return np.round(building_height / AVG_FLOOR_HEIGHT)