diff --git a/tokio/src/timer/delay.rs b/tokio/src/timer/delay.rs
index a48510f4b14..a4e9e32528f 100644
--- a/tokio/src/timer/delay.rs
+++ b/tokio/src/timer/delay.rs
@@ -21,6 +21,7 @@ use std::time::{Duration, Instant};
 ///
 /// [`new`]: #method.new
 #[derive(Debug)]
+#[must_use = "futures do nothing unless you `.await` or poll them"]
 pub struct Delay {
     /// The link between the `Delay` instance at the timer that drives it.
     ///