diff --git a/docs/content/2.guide/2.features/6.state-management.md b/docs/content/2.guide/2.features/6.state-management.md
index 727064711ce..96e81ee150e 100644
--- a/docs/content/2.guide/2.features/6.state-management.md
+++ b/docs/content/2.guide/2.features/6.state-management.md
@@ -10,6 +10,9 @@ Nuxt provides `useState` composable to create a reactive and SSR-friendly shared
 ::alert{icon=👉}
 `useState` only works during `setup` or [`Lifecycle Hooks`](https://vuejs.org/api/composition-api-lifecycle.html#composition-api-lifecycle-hooks).
 ::
+::alert{type=warning}
+Note that data inside `useState` must be serializable. This means you can't use functions or classes in `useState`.
+::
 
 ## Best practices