diff --git a/irisia-book/src/get_started/first_window.md b/irisia-book/src/get_started/first_window.md
index c5d43b8..def93e8 100644
--- a/irisia-book/src/get_started/first_window.md
+++ b/irisia-book/src/get_started/first_window.md
@@ -37,6 +37,7 @@ use irisia::{
     textbox::TextBox,
     Element,
     render_fn,
+    element::{NeverInitalized, NoProps},
 };
 
 #[derive(Default)]
@@ -49,6 +50,13 @@ impl Element for MyApp {
             text: "hello world"
         }
     }
+
+    fn create(_: irisia::element::RuntimeInit<Self>) -> Self {
+        Self{}
+    }
+
+    type Props<'a> = NoProps;
+    type ChildProps<'a> = NeverInitalized;
 }
 ```
 
@@ -81,7 +89,7 @@ use irisia::{
 #
 #[irisia::main]
 async fn main() {
-    Window::new::<MyApp>("my first app").await.join().await;
+    Window::new::<MyApp>("my first app").await.unwrap().join().await;
 }
 ```
 
diff --git a/irisia-core/Cargo.toml b/irisia-core/Cargo.toml
index 06091c3..7d04bb4 100644
--- a/irisia-core/Cargo.toml
+++ b/irisia-core/Cargo.toml
@@ -11,4 +11,4 @@ irisia_backend = { path = "../irisia-backend", features = ["fps_recorder"] }
 anyhow = "1"
 take_mut = "0.2"
 smallvec = "1.9"
-tokio = { version = "1.28", features = ["sync", "time", "rt-multi-thread"] }
+tokio = { version = "1.28", features = ["sync", "time", "macros", "rt-multi-thread"] }