2 files changed, 2 insertions, 1 deletions

diff --git a/lib/libc/gen/sem.c b/lib/libc/gen/sem.c
index e9ae6691090d..842298f4d2a3 100644
--- a/lib/libc/gen/sem.c
+++ b/lib/libc/gen/sem.c
@@ -434,7 +434,7 @@ _libc_sem_post_compat(sem_t *sem)
 		return ksem_post((*sem)->semid);
 
 	atomic_add_rel_int(&(*sem)->count, 1);
-
+	rmb();
 	if ((*sem)->nwaiters)
 		return _umtx_wake(&(*sem)->count);
 	return (0);
diff --git a/lib/libc/gen/sem_new.c b/lib/libc/gen/sem_new.c
index 2698b4056536..1480afb3a6c2 100644
--- a/lib/libc/gen/sem_new.c
+++ b/lib/libc/gen/sem_new.c
@@ -332,6 +332,7 @@ _sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
 static __inline int
 usem_wake(struct _usem *sem)
 {
+	rmb();
 	if (!sem->_has_waiters)
 		return (0);
 	return _umtx_op(sem, UMTX_OP_SEM_WAKE, 0, NULL, NULL);