diff --git a/src/sync/mod.rs b/src/sync/mod.rs
index b9162f14..82759fb6 100644
--- a/src/sync/mod.rs
+++ b/src/sync/mod.rs
@@ -192,5 +192,8 @@ cfg_unstable! {
 
 pub(crate) mod waker_set;
 pub(crate) use waker_set::WakerSet;
-pub(crate) mod spin_lock;
-pub(crate) use spin_lock::Spinlock;
+
+cfg_default! {
+    pub(crate) mod spin_lock;
+    pub(crate) use spin_lock::Spinlock;
+}