diff --git a/backend/pashub_fetcher/tests/test_core_files.py b/backend/pashub_fetcher/tests/test_core_files.py
index 85e7607e..7b991c23 100644
--- a/backend/pashub_fetcher/tests/test_core_files.py
+++ b/backend/pashub_fetcher/tests/test_core_files.py
@@ -130,3 +130,14 @@ def test_core_file_for_mtip_substring_returns_medium_term_improvement_plan() ->
 
     # Assert
     assert result == CoreFiles.MEDIUM_TERM_IMPROVEMENT_PLAN
+
+
+def test_core_file_for_osm_pattern_returns_retrofit_design_doc_without_evidence_category() -> None:
+    # Arrange
+    filename = "2512-OSM-H21M900-XX-DR-N-A_Lord Nelson Street 018.pdf"
+
+    # Act
+    result = core_file_for(filename)
+
+    # Assert
+    assert result == CoreFiles.RETROFIT_DESIGN_DOC