diff --git a/baselines/dom.generated.d.ts b/baselines/dom.generated.d.ts
index 87a7e7c49..6af3fa54d 100644
--- a/baselines/dom.generated.d.ts
+++ b/baselines/dom.generated.d.ts
@@ -6062,6 +6062,7 @@ interface HTMLObjectElement extends HTMLElement, GetSVGDocument {
      * Returns whether an element will successfully validate based on forms validation rules and constraints.
      */
     readonly willValidate: boolean;
+    typemustmatch: boolean;
     /**
      * Returns whether a form will validate when it is submitted, without having to submit it.
      */
diff --git a/inputfiles/addedTypes.json b/inputfiles/addedTypes.json
index 89caf3d78..32816fc56 100644
--- a/inputfiles/addedTypes.json
+++ b/inputfiles/addedTypes.json
@@ -2476,6 +2476,12 @@
         "name": "control",
         "type": "HTMLInputElement | null"
     },
+    {
+        "kind": "property",
+        "interface": "HTMLObjectElement",
+        "name": "typemustmatch",
+        "type": "boolean"
+    },
     {
         "kind": "property",
         "interface": "File",