diff --git a/libc/private/thread_private.h b/libc/private/thread_private.h
index b8b1a81..2e3ac3d 100644
--- a/libc/private/thread_private.h
+++ b/libc/private/thread_private.h
@@ -46,8 +46,9 @@
 __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()
+#define _ARC4_LOCK() _thread_arc4_lock()
+#define _ARC4_UNLOCK() _thread_arc4_unlock()
+#define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
 
 __END_DECLS