diff --git a/app/models/verification/residence.rb b/app/models/verification/residence.rb
index 7595549b9..9215fcebd 100644
--- a/app/models/verification/residence.rb
+++ b/app/models/verification/residence.rb
@@ -19,7 +19,7 @@ class Verification::Residence
     self.date_of_birth = parse_date('date_of_birth', attrs)
     attrs = remove_date('date_of_birth', attrs)
     super
-    self.document_number.upcase!
+    self.document_number.upcase! unless self.document_number.blank?
   end
 
   def save