diff --git a/Service/Monitor.php b/Service/Monitor.php
index efb8c63..b2be08e 100644
--- a/Service/Monitor.php
+++ b/Service/Monitor.php
@@ -30,7 +30,9 @@ class Monitor {
 				] );
 			}
 		} else {
-			wp_clear_scheduled_hook( 'wp_china_yes_monitor' );
+			if ( wp_get_scheduled_event( 'wp_china_yes_monitor' ) ) {
+				wp_clear_scheduled_hook( 'wp_china_yes_monitor' );
+			}
 		}
 	}