Index: thread/rthread_libc.c
===================================================================
RCS file: /cvs/src/lib/libc/thread/rthread_libc.c,v
diff -u -p -r1.4 rthread_libc.c
--- thread/rthread_libc.c	6 Jan 2021 19:54:17 -0000	1.4
+++ thread/rthread_libc.c	12 Jul 2025 08:53:06 -0000
@@ -303,18 +247,18 @@ _thread_atfork_unlock(void)
 /*
  * arc4random lock
  */
-static _atomic_lock_t arc4_lock = _SPINLOCK_UNLOCKED;
+static struct __cmtx arc4_lock = __CMTX_INITIALIZER();
 
 void
 _thread_arc4_lock(void)
 {
-	_spinlock(&arc4_lock);
+	__cmtx_enter(&arc4_lock);
 }
 
 void
 _thread_arc4_unlock(void)
 {
-	_spinunlock(&arc4_lock);
+	__cmtx_leave(&arc4_lock);
 }
 
 pid_t