diff --git a/tests/ui/consider-restricting.stderr b/tests/ui/consider-restricting.stderr
index 251168b..5f7fd00 100644
--- a/tests/ui/consider-restricting.stderr
+++ b/tests/ui/consider-restricting.stderr
@@ -4,6 +4,7 @@ error: future cannot be sent between threads safely
 16 |     async fn publish<T: IntoUrl>(&self, url: T) {}
    |                                                 ^^ future created by async block is not `Send`
    |
+   = note: consider using `std::sync::Arc<T>`; for more information visit <https://doc.rust-lang.org/book/ch16-03-shared-state.html>
 note: captured value is not `Send`
   --> tests/ui/consider-restricting.rs:16:41
    |
@@ -21,6 +22,7 @@ error: future cannot be sent between threads safely
 23 |     async fn publish<T>(&self, url: T) {}
    |                                        ^^ future created by async block is not `Send`
    |
+   = note: consider using `std::sync::Arc<T>`; for more information visit <https://doc.rust-lang.org/book/ch16-03-shared-state.html>
 note: captured value is not `Send`
   --> tests/ui/consider-restricting.rs:23:32
    |
diff --git a/tests/ui/send-not-implemented.stderr b/tests/ui/send-not-implemented.stderr
index 2710276..b8aedfd 100644
--- a/tests/ui/send-not-implemented.stderr
+++ b/tests/ui/send-not-implemented.stderr
@@ -10,6 +10,7 @@ error: future cannot be sent between threads safely
    | |_____^ future created by async block is not `Send`
    |
    = help: within `[async block@$DIR/tests/ui/send-not-implemented.rs:8:26: 12:6]`, the trait `Send` is not implemented for `MutexGuard<'_, ()>`
+   = note: consider using `std::sync::Arc<MutexGuard<'_, ()>>`; for more information visit <https://doc.rust-lang.org/book/ch16-03-shared-state.html>
 note: future is not `Send` as this value is used across an await
   --> tests/ui/send-not-implemented.rs:11:13
    |
@@ -34,6 +35,7 @@ error: future cannot be sent between threads safely
    | |_____^ future created by async block is not `Send`
    |
    = help: within `[async block@$DIR/tests/ui/send-not-implemented.rs:14:38: 19:6]`, the trait `Send` is not implemented for `MutexGuard<'_, ()>`
+   = note: consider using `std::sync::Arc<MutexGuard<'_, ()>>`; for more information visit <https://doc.rust-lang.org/book/ch16-03-shared-state.html>
 note: future is not `Send` as this value is used across an await
   --> tests/ui/send-not-implemented.rs:17:13
    |