diff --git a/library/std/src/sys/hermit/mutex.rs b/library/std/src/sys/hermit/mutex.rs
index e12c2f4e00c50..f988a019cfedb 100644
--- a/library/std/src/sys/hermit/mutex.rs
+++ b/library/std/src/sys/hermit/mutex.rs
@@ -155,7 +155,7 @@ pub struct Mutex {
     inner: Spinlock<MutexInner>,
 }
 
-pub type MovableMutex = Mutex;
+pub type MovableMutex = Box<Mutex>;
 
 unsafe impl Send for Mutex {}
 unsafe impl Sync for Mutex {}