diff --git a/book.json b/book.json
index a50760e..e757943 100644
--- a/book.json
+++ b/book.json
@@ -20,8 +20,8 @@
         "highlight",
         "back-to-top-button",
         "chapter-fold",
-        "page-treeview",
-        "pageview-count"
+        "pageview-count",
+        "flexible-alerts"
     ],
     "pluginsConfig": {
         "github": {