diff --git a/backend/condition/lookups/uprn_lookup.py b/backend/condition/lookups/uprn_lookup.py
index be8535bd..87cc54fa 100644
--- a/backend/condition/lookups/uprn_lookup.py
+++ b/backend/condition/lookups/uprn_lookup.py
@@ -3,5 +3,5 @@ from typing import Dict
 
 
 class UprnLookup(ABC):
-    def get_location_ref_to_uprn_map() -> Dict[str, int]:
+    def get_location_ref_to_uprn_map(self, lookup_filepath: str) -> Dict[str, int]:
         pass
diff --git a/backend/condition/lookups/uprn_lookup_local.py b/backend/condition/lookups/uprn_lookup_local.py
index bb4962e5..7bf7a575 100644
--- a/backend/condition/lookups/uprn_lookup_local.py
+++ b/backend/condition/lookups/uprn_lookup_local.py
@@ -3,5 +3,5 @@ from backend.condition.lookups.uprn_lookup import UprnLookup
 
 
 class UprnLookupLocal(UprnLookup):
-    def get_location_ref_to_uprn_map() -> Dict[str, int]:
+    def get_location_ref_to_uprn_map(self, lookup_filepath: str) -> Dict[str, int]:
         raise NotImplementedError
diff --git a/backend/condition/lookups/uprn_lookup_s3.py b/backend/condition/lookups/uprn_lookup_s3.py
index 83d6032c..e73bffaf 100644
--- a/backend/condition/lookups/uprn_lookup_s3.py
+++ b/backend/condition/lookups/uprn_lookup_s3.py
@@ -3,5 +3,5 @@ from backend.condition.lookups.uprn_lookup import UprnLookup
 
 
 class UprnLookupS3(UprnLookup):
-    def get_location_ref_to_uprn_map() -> Dict[str, int]:
+    def get_location_ref_to_uprn_map(self, lookup_filepath: str) -> Dict[str, int]:
         raise NotImplementedError