diff --git a/src/underscore_device/structure/instance.rs b/src/underscore_device/structure/instance.rs
index 7fe75fa1..a45dd28e 100644
--- a/src/underscore_device/structure/instance.rs
+++ b/src/underscore_device/structure/instance.rs
@@ -64,6 +64,7 @@ impl InstanceElement {
     ///
     ///
     pub fn add_alert(&mut self, alert: Alert) {
+        self.alerts.clear();
         self.alerts.push(alert);
     }