diff --git a/Assets/YooAsset/Samples~/Extension Sample/Runtime/PanelMonitor/PanelMonitor.cs b/Assets/YooAsset/Samples~/Extension Sample/Runtime/PanelMonitor/PanelMonitor.cs
index 83adc5e8..54369833 100644
--- a/Assets/YooAsset/Samples~/Extension Sample/Runtime/PanelMonitor/PanelMonitor.cs	
+++ b/Assets/YooAsset/Samples~/Extension Sample/Runtime/PanelMonitor/PanelMonitor.cs	
@@ -1,4 +1,4 @@
-#if UNITY_EDITOR
+#if UNITY_EDITOR && UNITY_2021_3_OR_NEWER
 using System.IO;
 using UnityEngine;
 using UnityEngine.UI;