diff --git a/backend/pashub_fetcher/tests/test_pashub_client.py b/backend/pashub_fetcher/tests/test_pashub_client.py
index 334f2de0..646ff3bc 100644
--- a/backend/pashub_fetcher/tests/test_pashub_client.py
+++ b/backend/pashub_fetcher/tests/test_pashub_client.py
@@ -116,6 +116,29 @@ def test_select_latest_core_files_returns_single_retrofit_design_doc() -> None:
     assert result[CoreFiles.RETROFIT_DESIGN_DOC].file_name == "2512-OSM-H21M900-XX-DR-N-A_Lord Nelson Street 018.pdf"
 
 
+def test_select_latest_core_files_osm_candidate_wins_over_non_osm() -> None:
+    # Arrange - the non-OSM file is newer but should lose to the OSM file
+    client = make_client()
+    files = [
+        make_file(
+            file_name="2512-OSM-H21M900-XX-DR-N-A_Lord Nelson Street 018.pdf",
+            evidence_category="retrofit design",
+            created_utc="2024-01-01T00:00:00",
+        ),
+        make_file(
+            file_name="Retrofit Design Doc non-osm variant.pdf",
+            evidence_category="retrofit design",
+            created_utc="2024-06-01T00:00:00",
+        ),
+    ]
+
+    # Act
+    result = client._select_latest_core_files(files)
+
+    # Assert
+    assert result[CoreFiles.RETROFIT_DESIGN_DOC].file_name == "2512-OSM-H21M900-XX-DR-N-A_Lord Nelson Street 018.pdf"
+
+
 def test_get_core_file_type_evidence_category_match_is_case_insensitive() -> None:
     # Arrange
     client = make_client()