1 files changed, 3 insertions, 0 deletions
diff --git a/library/std/src/sys/sync/mod.rs b/library/std/src/sys/sync/mod.rs
index 52fac5902a2..0691e967851 100644
--- a/library/std/src/sys/sync/mod.rs
+++ b/library/std/src/sys/sync/mod.rs
@@ -1,11 +1,14 @@
 mod condvar;
 mod mutex;
 mod once;
+mod once_box;
 mod rwlock;
 mod thread_parking;
 
 pub use condvar::Condvar;
 pub use mutex::Mutex;
 pub use once::{Once, OnceState};
+#[allow(unused)] // Only used on some platforms.
+use once_box::OnceBox;
 pub use rwlock::RwLock;
 pub use thread_parking::Parker;