diff --git a/libc/private/thread_private.h b/libc/private/thread_private.h
index 1f9eeb6..1a13690 100644
--- a/libc/private/thread_private.h
+++ b/libc/private/thread_private.h
@@ -29,7 +29,6 @@
 
 #define _ARC4_LOCK() _thread_arc4_lock()
 #define _ARC4_UNLOCK() _thread_arc4_unlock()
-#define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
 
 extern volatile sig_atomic_t _rs_forked;