diff --git a/app/code/Magento/Checkout/i18n/en_US.csv b/app/code/Magento/Checkout/i18n/en_US.csv
index 8f84275b5488d..53e6ef67d68cd 100644
--- a/app/code/Magento/Checkout/i18n/en_US.csv
+++ b/app/code/Magento/Checkout/i18n/en_US.csv
@@ -176,3 +176,4 @@ Payment,Payment
 "Not yet calculated","Not yet calculated"
 "We received your order!","We received your order!"
 "Thank you for your purchase!","Thank you for your purchase!"
+"optional", "optional"