diff --git a/backend/address2UPRN/main.py b/backend/address2UPRN/main.py
index 98f8c65b..fad5c64e 100644
--- a/backend/address2UPRN/main.py
+++ b/backend/address2UPRN/main.py
@@ -78,7 +78,8 @@ def get_uprn_with_epc_df(
     # Safe to return the agreed UPRN
     found_uprn = top_rank_df.iloc[0]["uprn"]
 
-    if found_uprn == "":
+    # Handling numeric missingness in new api
+    if found_uprn in ["", "nan"]:
         return None
 
     if verbose:
diff --git a/backend/address2UPRN/tests/test_data.csv b/backend/address2UPRN/tests/test_data.csv
index aaeee66d..ee23813b 100644
--- a/backend/address2UPRN/tests/test_data.csv
+++ b/backend/address2UPRN/tests/test_data.csv
@@ -117,14 +117,14 @@ FLAT 43 Goodstone Court,HA1 4FL,10070269095
 10 Genteel House Samara Drive,UB1 1FJ,12189844
 1 ASH TREE HOUSE,SE5 0TE,None
 "Flat 1 Ash Tree House, 2, Thompson Avenue",SE5 0TE,10009803979
-3 ASH TREE HOUSE,SE5 0TE,10009803981
+3 ASH TREE HOUSE,SE5 0TE,None
 Flat 3 ASH TREE HOUSE,SE5 0TE,10009803981
-5 ASH TREE HOUSE,SE5 0TE,10009803983
+5 ASH TREE HOUSE,SE5 0TE,None
 Flat 5 ASH TREE HOUSE,SE5 0TE,10009803983
 Flat 8 ASH TREE HOUSE,SE5 0TE,10009803986
 8 ASH TREE HOUSE,SE5 0TE,None
 Flat 12 ASH TREE HOUSE,SE5 0TE,10009803990
-12 ASH TREE HOUSE,SE5 0TE,10009803990
+12 ASH TREE HOUSE,SE5 0TE,None
 FLAT 1 599 HARROW ROAD,W10 4RA,217113930
 FLAT 2 599 HARROW ROAD,W10 4RA,217113931
 FLAT 3 599 HARROW ROAD,W10 4RA,None