diff --git a/src/libstd/sync/condvar.rs b/src/libstd/sync/condvar.rs
index 7f9b56676288..3e40cbb37e3d 100644
--- a/src/libstd/sync/condvar.rs
+++ b/src/libstd/sync/condvar.rs
@@ -469,7 +469,7 @@ impl Condvar {
     /// let result = cvar.wait_timeout_until(
     ///     lock.lock().unwrap(),
     ///     Duration::from_millis(100),
-    ///     |started| started,
+    ///     |&mut started| started,
     /// ).unwrap();
     /// if result.1.timed_out() {
     ///     // timed-out without the condition ever evaluating to true.