diff --git a/app/forms/waste_carriers_engine/base_form.rb b/app/forms/waste_carriers_engine/base_form.rb
index 0b9894bb4..dac203499 100644
--- a/app/forms/waste_carriers_engine/base_form.rb
+++ b/app/forms/waste_carriers_engine/base_form.rb
@@ -71,7 +71,7 @@ def transient_registration_valid?
       return if transient_registration.valid?
 
       transient_registration.errors.each do |_attribute, message|
-        errors[:base] << message
+        errors.add(:base, message)
       end
     end