diff --git a/typescript/base/tree/ztree/treeview.ts b/typescript/base/tree/ztree/treeview.ts
index 0bdf2ac30b..5ca3995816 100644
--- a/typescript/base/tree/ztree/treeview.ts
+++ b/typescript/base/tree/ztree/treeview.ts
@@ -62,7 +62,7 @@ export declare class TreeView extends Pane {
     getValue(): TreeValue;
 
     // @ts-ignore
-    populate(config: {[key: string]: any}): void;
+    populate(config?: {[key: string]: any}): void;
 }
 
 export interface TreeValue {