diff --git a/baselines/dom.generated.d.ts b/baselines/dom.generated.d.ts
index ddc3e33c8..33ec028ae 100644
--- a/baselines/dom.generated.d.ts
+++ b/baselines/dom.generated.d.ts
@@ -8738,7 +8738,7 @@ interface Node extends EventTarget {
     contains(child: Node): boolean;
     hasAttributes(): boolean;
     hasChildNodes(): boolean;
-    insertBefore(newChild: Node, refChild?: Node): Node;
+    insertBefore(newChild: Node, refChild: Node): Node;
     isDefaultNamespace(namespaceURI: string | null): boolean;
     isEqualNode(arg: Node): boolean;
     isSameNode(other: Node): boolean;
diff --git a/inputfiles/overridingTypes.json b/inputfiles/overridingTypes.json
index 4e01ad3ea..075012627 100644
--- a/inputfiles/overridingTypes.json
+++ b/inputfiles/overridingTypes.json
@@ -1,4 +1,10 @@
  [
+    {
+        "kind": "method",
+        "interface": "Node",
+        "name": "insertBefore",
+        "signatures": ["insertBefore(newChild: Node, refChild: Node): Node"]
+    },
     {
         "kind": "method",
         "interface": "HTMLCollection",