diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index f1b560b9b9685..3320ebdf821d0 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -384,7 +384,10 @@ impl<T: ?Sized> Box<T> {
     ///
     /// unsafe {
     ///     let ptr = alloc(Layout::new::<i32>()) as *mut i32;
-    ///     *ptr = 5;
+    ///     // In general .write is required to avoid attempting to destruct
+    ///     // the (uninitialized) previous contents of `ptr`, though for this
+    ///     // simple example `*ptr = 5` would have worked as well.
+    ///     ptr.write(5);
     ///     let x = Box::from_raw(ptr);
     /// }
     /// ```