diff -ur a/dist/aclocal/mutex.m4 b/dist/aclocal/mutex.m4
--- a/dist/aclocal/mutex.m4	1969-12-31 19:00:01.000000000 -0500
+++ b/dist/aclocal/mutex.m4	2023-06-05 19:14:47.214158196 -0400
@@ -372,10 +376,11 @@
 
 # _spin_lock_try/_spin_unlock: Apple/Darwin
 if test "$db_cv_mutex" = no; then
-AC_TRY_LINK(,[
-	int x;
-	_spin_lock_try(&x);
-	_spin_unlock(&x);
+AC_TRY_LINK([
+#include <os/lock.h>],[
+	os_unfair_lock x = OS_UNFAIR_LOCK_INIT;
+	bool _ = os_unfair_lock_trylock(&x);
+	os_unfair_lock_unlock(&x);
 ], [db_cv_mutex=Darwin/_spin_lock_try])
 fi
 
diff -ur a/dbinc/mutex_int.h b/dbinc/mutex_int.h
--- a/dbinc/mutex_int.h	1969-12-31 19:00:01.000000000 -0500
+++ b/dbinc/mutex_int.h	2023-06-05 19:15:37.510514745 -0400
@@ -154,14 +154,13 @@
  * Apple/Darwin library functions.
  *********************************************************************/
 #ifdef HAVE_MUTEX_DARWIN_SPIN_LOCK_TRY
-typedef u_int32_t tsl_t;
+#include <os/lock.h>
+typedef os_unfair_lock tsl_t;
 
 #ifdef LOAD_ACTUAL_MUTEX_CODE
-extern int _spin_lock_try(tsl_t *);
-extern void _spin_unlock(tsl_t *);
-#define	MUTEX_SET(tsl)          _spin_lock_try(tsl)
-#define	MUTEX_UNSET(tsl)        _spin_unlock(tsl)
-#define	MUTEX_INIT(tsl)         (MUTEX_UNSET(tsl), 0)
+#define	MUTEX_SET(tsl)          os_unfair_lock_trylock(tsl)
+#define	MUTEX_UNSET(tsl)        os_unfair_lock_unlock(tsl)
+#define	MUTEX_INIT(tsl)         ({ *(tsl) = OS_UNFAIR_LOCK_INIT; tsl; })
 #endif
 #endif
 
diff -ur a/dbinc/mutex_int.h b/dbinc/mutex_int.h
--- a/dbinc_auto/mutex_ext.h	1969-12-31 19:00:01.000000000 -0500
+++ b/dbinc_auto/mutex_ext.h	2023-07-01 22:38:20.749201366 -0400
@@ -34,6 +34,9 @@
 #if !defined(HAVE_ATOMIC_SUPPORT) && defined(HAVE_MUTEX_SUPPORT)
 atomic_value_t __atomic_dec __P((ENV *, db_atomic_t *));
 #endif
+#if !defined(HAVE_ATOMIC_SUPPORT) && defined(HAVE_MUTEX_SUPPORT)
+int atomic_compare_exchange __P((ENV *, db_atomic_t *, atomic_value_t, atomic_value_t));
+#endif
 int __db_pthread_mutex_init __P((ENV *, db_mutex_t, u_int32_t));
 int __db_pthread_mutex_lock __P((ENV *, db_mutex_t));
 #if defined(HAVE_SHARED_LATCHES)