diff --git a/domains/optional-list.txt b/domains/optional-list.txt
index 50e0e85..08689cd 100644
--- a/domains/optional-list.txt
+++ b/domains/optional-list.txt
@@ -158,3 +158,7 @@ track.ucas.com
 
 # Amazon AWS (???) - whitelist to make Kryptonite work
 sqs.us-east-1.amazonaws.com
+
+# National Express, UK (nationalexpress.com/en) - Unable to book journey
+
+cdns.gigya.com