diff --git a/api/MathMLElement.json b/api/MathMLElement.json
index 0f08f6673d1331..6d3a56c5e892ff 100644
--- a/api/MathMLElement.json
+++ b/api/MathMLElement.json
@@ -35,6 +35,7 @@
       },
       "attributeStyleMap": {
         "__compat": {
+          "mdn_url": "https://developer.mozilla.org/docs/Web/API/MathMLElement/attributeStyleMap",
           "spec_url": "https://drafts.css-houdini.org/css-typed-om/#dom-elementcssinlinestyle-attributestylemap",
           "support": {
             "chrome": {
diff --git a/api/SVGElement.json b/api/SVGElement.json
index b0aeed280cf227..918e379d05ffba 100644
--- a/api/SVGElement.json
+++ b/api/SVGElement.json
@@ -45,6 +45,7 @@
       },
       "attributeStyleMap": {
         "__compat": {
+          "mdn_url": "https://developer.mozilla.org/docs/Web/API/SVGElement/attributeStyleMap",
           "spec_url": "https://drafts.css-houdini.org/css-typed-om/#dom-elementcssinlinestyle-attributestylemap",
           "support": {
             "chrome": {