diff --git a/packages/runtime-core/src/apiWatch.ts b/packages/runtime-core/src/apiWatch.ts
index 4a41485629c..a58f4d394f8 100644
--- a/packages/runtime-core/src/apiWatch.ts
+++ b/packages/runtime-core/src/apiWatch.ts
@@ -428,7 +428,7 @@ export function createPathGetter(ctx: any, path: string) {
   }
 }
 
-export function traverse(value: unknown, seen: Set<unknown> = new Set()) {
+export function traverse(value: unknown, seen?: Set<unknown>) {
   if (!isObject(value) || (value as any)[ReactiveFlags.SKIP]) {
     return value
   }