diff --git a/_config/config.yml b/_config/config.yml
index e1b7883722e..7109ca9397a 100644
--- a/_config/config.yml
+++ b/_config/config.yml
@@ -6,7 +6,7 @@ SilverStripe\Control\HTTP:
     max-age: 0
     must-revalidate: "true"
     no-transform: "true"
-  vary: "Cookie, X-Forwarded-Protocol, User-Agent, Accept"
+  vary: "Cookie, X-Forwarded-Protocol, X-Forwarded-Proto, User-Agent, Accept"
 SilverStripe\Core\Manifest\VersionProvider:
   modules:
     silverstripe/framework: Framework