diff --git a/lib/libc/stdlib/quick_exit.c b/lib/libc/stdlib/quick_exit.c
--- a/lib/libc/stdlib/quick_exit.c
+++ b/lib/libc/stdlib/quick_exit.c
@@ -2,6 +2,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  *
  * Copyright (c) 2011 David Chisnall
+ * Copyright (c) 2023 Klara, Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -29,42 +30,35 @@
 #include <sys/types.h>
 #include <machine/atomic.h>
 #include <stdlib.h>
-#include <pthread.h>
 
 /**
- * Linked list of quick exit handlers.  This is simpler than the atexit()
- * version, because it is not required to support C++ destructors or
- * DSO-specific cleanups.
+ * Linked list of quick exit handlers.  These will be invoked in reverse
+ * order of insertion when quick_exit() is called.  This is simpler than
+ * the atexit() version, because it is not required to support C++
+ * destructors or DSO-specific cleanups.
  */
 struct quick_exit_handler {
 	struct quick_exit_handler *next;
 	void (*cleanup)(void);
 };
 
-/**
- * Lock protecting the handlers list.
- */
-static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
-/**
- * Stack of cleanup handlers.  These will be invoked in reverse order when 
- */
 static struct quick_exit_handler *handlers;
 
 int
 at_quick_exit(void (*func)(void))
 {
 	struct quick_exit_handler *h;
-	
-	h = malloc(sizeof(*h));
+	int done;
 
+	h = malloc(sizeof(*h));
 	if (NULL == h)
 		return (1);
 	h->cleanup = func;
-	pthread_mutex_lock(&atexit_mutex);
 	h->next = handlers;
-	__compiler_membar();
-	handlers = h;
-	pthread_mutex_unlock(&atexit_mutex);
+	do {
+		done = atomic_fcmpset_rel_ptr((uintptr_t *)&handlers,
+		    (uintptr_t *)&h->next, (uintptr_t)h);
+	} while (__predict_false(!done));
 	return (0);
 }
 
@@ -77,8 +71,8 @@
 	 * XXX: The C++ spec requires us to call std::terminate if there is an
 	 * exception here.
 	 */
-	for (h = handlers; NULL != h; h = h->next) {
-		__compiler_membar();
+	h = (void *)atomic_load_acq_ptr((uintptr_t *)&handlers);
+	for (; NULL != h; h = h->next) {
 		h->cleanup();
 	}
 	_Exit(status);