diff --git a/datatypes/epc/domain/tests/test_from_site_notes.py b/datatypes/epc/domain/tests/test_from_site_notes.py
index bde715237..ad18a969e 100644
--- a/datatypes/epc/domain/tests/test_from_site_notes.py
+++ b/datatypes/epc/domain/tests/test_from_site_notes.py
@@ -160,8 +160,9 @@ class TestFromSiteNotesExample1:
     # --- main heating ---
 
     def test_main_heating_fuel(self, result: EpcPropertyData) -> None:
-        # heating_and_hot_water.main_heating.fuel: "Mains gas"
-        assert result.sap_heating.main_heating_details[0].main_fuel_type == "Mains gas"
+        # heating_and_hot_water.main_heating.fuel: "Mains gas" is normalized
+        # at the mapper boundary to SAP fuel code 26 (matching Elmhurst).
+        assert result.sap_heating.main_heating_details[0].main_fuel_type == 26
 
     def test_main_heating_emitter(self, result: EpcPropertyData) -> None:
         # heating_and_hot_water.main_heating.emitter: "Radiators"