diff --git a/library/std/src/sys/unsupported/mutex.rs b/library/std/src/sys/unsupported/mutex.rs
index a28f2cf4ffe..06ea9a1e2c1 100644
--- a/library/std/src/sys/unsupported/mutex.rs
+++ b/library/std/src/sys/unsupported/mutex.rs
@@ -4,7 +4,7 @@ pub struct Mutex {
     locked: UnsafeCell<bool>,
 }
 
-pub type MovableMutex = Box<Mutex>;
+pub type MovableMutex = Mutex;
 
 unsafe impl Send for Mutex {}
 unsafe impl Sync for Mutex {} // no threads on this platform