diff --git a/app/models/user_upgrade.rb b/app/models/user_upgrade.rb
index 8551c7951..6ec4f2488 100644
--- a/app/models/user_upgrade.rb
+++ b/app/models/user_upgrade.rb
@@ -160,7 +160,7 @@ class UserUpgrade < ApplicationRecord
         client_reference_id: "user_upgrade_#{id}",
         customer_email: purchaser.email_address&.address,
         payment_method_types: methods,
-        allow_promotion_codes: allow_promotion_codes,
+        allow_promotion_codes: allow_promotion_codes.presence,
         line_items: [{
           price: price_id,
           quantity: 1,