diff --git a/saleor/account/i18n.py b/saleor/account/i18n.py
index 95e49b07895..189efc95612 100644
--- a/saleor/account/i18n.py
+++ b/saleor/account/i18n.py
@@ -201,9 +201,10 @@ def substitute_invalid_values(data):
             return
         if custom_names := VALID_ADDRESS_EXTENSION_MAP.get(country_code):
             for field_name, mapping in custom_names.items():
-                actual_value = data.get(field_name)
-                if actual_value in mapping:
-                    data[field_name] = mapping[actual_value]
+                actual_value = data.get(field_name, "").strip().lower()
+                mapping_adjusted = {k.strip().lower(): v for k, v in mapping.items()}
+                if actual_value in mapping_adjusted:
+                    data[field_name] = mapping_adjusted[actual_value]
 
 
 def get_address_form_class(country_code):
diff --git a/saleor/account/tests/test_account.py b/saleor/account/tests/test_account.py
index b846ebb64bd..f33d5d9b2c1 100644
--- a/saleor/account/tests/test_account.py
+++ b/saleor/account/tests/test_account.py
@@ -322,6 +322,10 @@ def test_customers_show_staff_with_order(admin_user, channel_USD):
         ("Dublin", "Co. Dublin", True),
         ("Co. Dublin", "Co. Dublin", True),
         ("Dummy Area", None, False),
+        ("dublin", "Co. Dublin", True),
+        (" dublin ", "Co. Dublin", True),
+        ("", "", True),
+        (None, "", True),
     ],
 )
 @patch.dict(