diff --git a/backend/pashub_fetcher/pashub_client.py b/backend/pashub_fetcher/pashub_client.py
index 11195960..d7200a1f 100644
--- a/backend/pashub_fetcher/pashub_client.py
+++ b/backend/pashub_fetcher/pashub_client.py
@@ -87,7 +87,7 @@ class PashubClient:
             return None
 
     def _get_core_file_type(self, file: EvidenceFileData) -> Optional[CoreFiles]:
-        if file.evidence_category == "retrofit design":
+        if file.evidence_category is not None and file.evidence_category.lower() == "retrofit design":
             return CoreFiles.RETROFIT_DESIGN_DOC
 
         for core_file in CoreFiles: