diff --git a/css/selectors/backdrop.json b/css/selectors/backdrop.json
index 61650521571fa6..f56a5b5c01cde8 100644
--- a/css/selectors/backdrop.json
+++ b/css/selectors/backdrop.json
@@ -5,7 +5,7 @@
         "__compat": {
           "description": "<code>::backdrop</code>",
           "mdn_url": "https://developer.mozilla.org/docs/Web/CSS/::backdrop",
-          "spec_url": "https://fullscreen.spec.whatwg.org/#::backdrop-pseudo-element",
+          "spec_url": "https://w3c.github.io/csswg-drafts/css-position-4/#backdrop",
           "support": {
             "chrome": [
               {