diff --git a/tests/backend/app/modelling/test_property_filters.py b/tests/backend/app/modelling/test_property_filters.py
index b7d029368..dda558547 100644
--- a/tests/backend/app/modelling/test_property_filters.py
+++ b/tests/backend/app/modelling/test_property_filters.py
@@ -1,6 +1,6 @@
 from typing import Optional
 
-from sqlalchemy import Engine
+from sqlalchemy import Engine, text
 from sqlmodel import Session
 
 from backend.app.modelling.property_filters import (
@@ -220,24 +220,39 @@ def test_epc_without_property_type_falls_back_to_dwelling_type(
     assert [p.property_id for p in resolved] == [fallback]
 
 
-def test_property_without_epc_falls_back_to_the_legacy_column(
-    db_engine: Engine,
-) -> None:
-    # arrange — no override, no EPC rows; only property.property_type
+def test_legacy_property_columns_are_ignored(db_engine: Engine) -> None:
+    """property.property_type / built_form are legacy: with no override and no
+    EPC the property is "Unknown", whatever the legacy columns say (ADR-0056
+    amendment)."""
+    # arrange — no override, no EPC rows; the FE-owned legacy column exists in
+    # prod but is no longer mirrored, so add it here and set a value that must
+    # not count
     with Session(db_engine) as session:
         legacy = _seed_property(session, portfolio_id=814)
-        session.get_one(PropertyRow, legacy).property_type = "Bungalow"
+        session.connection().execute(
+            text("ALTER TABLE property ADD COLUMN IF NOT EXISTS property_type TEXT")
+        )
+        session.connection().execute(
+            text("UPDATE property SET property_type = 'Bungalow' WHERE id = :id"),
+            {"id": legacy},
+        )
         session.commit()
 
         # act
-        resolved = resolve_filtered_property_ids(
+        as_bungalow = resolve_filtered_property_ids(
             session,
             portfolio_id=814,
             filters=PropertyGroupFilters(property_types=["Bungalow"]),
         )
+        as_unknown = resolve_filtered_property_ids(
+            session,
+            portfolio_id=814,
+            filters=PropertyGroupFilters(property_types=["Unknown"]),
+        )
 
     # assert
-    assert [p.property_id for p in resolved] == [legacy]
+    assert as_bungalow == []
+    assert [p.property_id for p in as_unknown] == [legacy]
 
 
 def test_unknown_is_a_selectable_property_type_bucket(db_engine: Engine) -> None: