diff --git a/typescript/core/utils/tree.ts b/typescript/core/utils/tree.ts
index 3ae195351e..99167c62d5 100644
--- a/typescript/core/utils/tree.ts
+++ b/typescript/core/utils/tree.ts
@@ -32,7 +32,7 @@ export declare class Tree {
   clear():void;
   initTree(nodes: any[]):void;
   toJSON<T>(node?: Node): T[];
-  toJSONWithNode<T>(node: Node): T[];
+  toJSONWithNode<T>(node?: Node): T[];
   search(root: Node, target?: any, param?: any): Node;
   traverse(callback: Function): void;
   recursion(callback: Function): void;
@@ -47,4 +47,4 @@ export declare class Tree {
   static transformToTreeFormat<T>(sNodes: T[]): Node[];
   static treeFormat(sNodes: Node | Node[]): Node[];
   static traversal(array: Node[], callback: Function, pNode: Node): void;
-}
\ No newline at end of file
+}