diff --git a/src/disco/constants.js b/src/disco/constants.js
index e12d06f4194..8200146514b 100644
--- a/src/disco/constants.js
+++ b/src/disco/constants.js
@@ -39,4 +39,5 @@ export const DISCO_DATA_GUID_IGNORE_LIST = [
   'screenshots@mozilla.org', // Firefox Screenshots
   'disable-prefetch@mozilla.org', // Disable Prefetch
   'activity-stream@mozilla.org', // Activity Stream
+  'disable-cert-transparency@mozilla.org', // Disable TLS Certificate Transparency
 ];