diff --git a/Userland/Libraries/LibWeb/DOM/DocumentType.idl b/Userland/Libraries/LibWeb/DOM/DocumentType.idl
index 7834d9d49d9..2c389387d2e 100644
--- a/Userland/Libraries/LibWeb/DOM/DocumentType.idl
+++ b/Userland/Libraries/LibWeb/DOM/DocumentType.idl
@@ -8,3 +8,5 @@ interface DocumentType : Node {
     readonly attribute DOMString publicId;
     readonly attribute DOMString systemId;
 };
+
+DocumentType includes ChildNode;