diff --git a/src/2_waker_context.md b/src/2_waker_context.md
index d7ec878..6c58ca8 100644
--- a/src/2_waker_context.md
+++ b/src/2_waker_context.md
@@ -56,15 +56,16 @@ trait SomeTrait { }
 
 fn main() {
     println!("======== The size of different pointers in Rust: ========");
-    println!("&dyn Trait:-----{}", size_of::<&dyn SomeTrait>());
-    println!("&[&dyn Trait]:--{}", size_of::<&[&dyn SomeTrait]>());
-    println!("Box<Trait>:-----{}", size_of::<Box<SomeTrait>>());
-    println!("&i32:-----------{}", size_of::<&i32>());
-    println!("&[i32]:---------{}", size_of::<&[i32]>());
-    println!("Box<i32>:-------{}", size_of::<Box<i32>>());
-    println!("&Box<i32>:------{}", size_of::<&Box<i32>>());
-    println!("[&dyn Trait;4]:-{}", size_of::<[&dyn SomeTrait; 4]>());
-    println!("[i32;4]:--------{}", size_of::<[i32; 4]>());
+    println!("&dyn Trait:------{}", size_of::<&dyn SomeTrait>());
+    println!("&[&dyn Trait]:---{}", size_of::<&[&dyn SomeTrait]>());
+    println!("Box<Trait>:------{}", size_of::<Box<SomeTrait>>());
+    println!("Box<Box<Trait>>:-{}", size_of::<Box<Box<SomeTrait>>>());
+    println!("&i32:------------{}", size_of::<&i32>());
+    println!("&[i32]:----------{}", size_of::<&[i32]>());
+    println!("Box<i32>:--------{}", size_of::<Box<i32>>());
+    println!("&Box<i32>:-------{}", size_of::<&Box<i32>>());
+    println!("[&dyn Trait;4]:--{}", size_of::<[&dyn SomeTrait; 4]>());
+    println!("[i32;4]:---------{}", size_of::<[i32; 4]>());
 }
 ```