diff --git a/packages/runtime-core/src/apiWatch.ts b/packages/runtime-core/src/apiWatch.ts
index 0e33193b2..eaa699ce7 100644
--- a/packages/runtime-core/src/apiWatch.ts
+++ b/packages/runtime-core/src/apiWatch.ts
@@ -309,7 +309,7 @@ function doWatch(
 
   let scheduler: ReactiveEffectOptions['scheduler']
   if (flush === 'sync') {
-    scheduler = job
+    scheduler = job as any // the scheduler function gets called directly
   } else if (flush === 'post') {
     scheduler = () => queuePostRenderEffect(job, instance && instance.suspense)
   } else {