diff --git a/http/headers/No-Vary-Search.json b/http/headers/No-Vary-Search.json
index 265d83e7015e10..ffc6c42ff95a43 100644
--- a/http/headers/No-Vary-Search.json
+++ b/http/headers/No-Vary-Search.json
@@ -4,6 +4,7 @@
       "No-Vary-Search": {
         "__compat": {
           "mdn_url": "https://developer.mozilla.org/docs/Web/HTTP/Headers/No-Vary-Search",
+          "spec_url": "https://httpwg.org/http-extensions/draft-ietf-httpbis-no-vary-search.html#section-2",
           "support": {
             "chrome": [
               {