diff --git a/axum-debug/tests/fail/not_send.stderr b/axum-debug/tests/fail/not_send.stderr
index d5dfaff2..5d8bc96e 100644
--- a/axum-debug/tests/fail/not_send.stderr
+++ b/axum-debug/tests/fail/not_send.stderr
@@ -4,7 +4,7 @@ error: future cannot be sent between threads safely
 4 | async fn handler() {
   | ^^^^^ future returned by `handler` is not `Send`
   |
-  = help: within `impl Future`, the trait `Send` is not implemented for `Rc<()>`
+  = help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `Rc<()>`
 note: future is not `Send` as this value is used across an await
  --> tests/fail/not_send.rs:6:5
   |