diff --git a/backend/addresses/Addresses.py b/backend/addresses/Addresses.py
index 9da55aa1..c1624522 100644
--- a/backend/addresses/Addresses.py
+++ b/backend/addresses/Addresses.py
@@ -1,4 +1,5 @@
 import warnings
+import pandas as pd
 from typing import Iterator
 from backend.addresses.Address import Address
 from datatypes.epc.property_type_built_form import PropertyType
@@ -121,7 +122,12 @@ class Addresses:
             except (TypeError, ValueError):
                 raise ValueError(f"Invalid UPRN value: {v}")
 
-        uprn = clean_uprn(row.get("uprn") or row.get("ordnance_survey_uprn"))
+        uprn_option1 = row.get("uprn")
+        uprn_option1 = uprn_option1 if not pd.isnull(uprn_option1) else None
+        uprn_option2 = row.get("ordnance_survey_uprn")
+        uprn_option2 = uprn_option2 if not pd.isnull(uprn_option2) else None
+
+        uprn = clean_uprn(uprn_option1 or uprn_option2)
 
         address = row.get("address") or row.get("domna_address_1") or ""
         full_address = row.get("domna_full_address") or address or ""