diff --git a/tests/repositories/property/test_landlord_override_overlays.py b/tests/repositories/property/test_landlord_override_overlays.py
index 20c79c1f..4c4a3403 100644
--- a/tests/repositories/property/test_landlord_override_overlays.py
+++ b/tests/repositories/property/test_landlord_override_overlays.py
@@ -47,6 +47,21 @@ def test_each_resolvable_component_produces_an_overlay() -> None:
     assert len(overlays) == 4
 
 
+def test_main_fuel_row_produces_a_heating_fuel_overlay() -> None:
+    # Arrange
+    overrides = ResolvedPropertyOverrides(
+        rows=(ResolvedPropertyOverride("main_fuel", 0, "mains gas"),)
+    )
+
+    # Act
+    overlays = overlays_from(overrides)
+
+    # Assert
+    assert len(overlays) == 1
+    assert overlays[0].heating is not None
+    assert overlays[0].heating.main_fuel_type == 26
+
+
 def test_unresolvable_rows_are_skipped() -> None:
     # Arrange — an "Unknown" property type and an unmapped wall material.
     overrides = ResolvedPropertyOverrides(