diff --git a/libc/private/thread_private.h b/libc/private/thread_private.h
index f731181..724808a 100644
--- a/libc/private/thread_private.h
+++ b/libc/private/thread_private.h
@@ -7,6 +7,8 @@
 
 #include <pthread.h>
 
+__BEGIN_DECLS
+
 /*
  * This file defines the thread library interface to libc.  Thread
  * libraries must implement the functions described here for proper
@@ -31,10 +33,18 @@
 #define _THREAD_PRIVATE_MUTEX_UNLOCK(name) \
 	pthread_mutex_unlock( &__THREAD_NAME(name)._private_lock )
 
-void	_thread_atexit_lock(void);
-void	_thread_atexit_unlock(void);
+__LIBC_HIDDEN__ void	_thread_atexit_lock(void);
+__LIBC_HIDDEN__ void	_thread_atexit_unlock(void);
 
 #define _ATEXIT_LOCK() _thread_atexit_lock()
 #define _ATEXIT_UNLOCK() _thread_atexit_unlock()
 
+__LIBC_HIDDEN__ void    _thread_arc4_lock(void);
+__LIBC_HIDDEN__ void    _thread_arc4_unlock(void);
+
+#define  _ARC4_LOCK() _thread_arc4_lock()
+#define  _ARC4_UNLOCK() _thread_arc4_unlock()
+
+__END_DECLS
+
 #endif /* _THREAD_PRIVATE_H_ */