diff --git a/src/core/xfa/xfa_object.js b/src/core/xfa/xfa_object.js
index e2ae8d6104dd4..41bc022ce7fde 100644
--- a/src/core/xfa/xfa_object.js
+++ b/src/core/xfa/xfa_object.js
@@ -560,9 +560,6 @@ class XFAObject {
       this[$content] = proto[$content];
     }
 
-    const newAncestors = new Set(ancestors);
-    newAncestors.add(proto);
-
     for (const unsetAttrName of this[_getUnsetAttributes](
       proto[_setAttributes]
     )) {