diff --git a/assets/themes/uk_addresses/uk_addresses.json b/assets/themes/uk_addresses/uk_addresses.json
index 2114beac2..296c12516 100644
--- a/assets/themes/uk_addresses/uk_addresses.json
+++ b/assets/themes/uk_addresses/uk_addresses.json
@@ -151,7 +151,7 @@
           },
           "freeform": {
             "key": "addr:housenumber",
-            "addExtraTags": "nohousenumber="
+            "addExtraTags": ["nohousenumber="]
           },
           "mappings": [
             {