diff --git a/sys/contrib/openzfs/lib/libspl/assert.c b/sys/contrib/openzfs/lib/libspl/assert.c
index e6e3008f0aa6..5b12c14acd6e 100644
--- a/sys/contrib/openzfs/lib/libspl/assert.c
+++ b/sys/contrib/openzfs/lib/libspl/assert.c
@@ -1,144 +1,163 @@
 /*
  * CDDL HEADER START
  *
  * The contents of this file are subject to the terms of the
  * Common Development and Distribution License (the "License").
  * You may not use this file except in compliance with the License.
  *
  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  * or https://opensource.org/licenses/CDDL-1.0.
  * See the License for the specific language governing permissions
  * and limitations under the License.
  *
  * When distributing Covered Code, include this CDDL HEADER in each
  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  * If applicable, add the following below this CDDL HEADER, with the
  * fields enclosed by brackets "[]" replaced with your own identifying
  * information: Portions Copyright [yyyy] [name of copyright owner]
  *
  * CDDL HEADER END
  */
 /*
  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 /*
  * Copyright (c) 2024, Rob Norris <robn@despairlabs.com>
  */
 
 #include <assert.h>
 #include <pthread.h>
 
 #if defined(__linux__)
 #include <errno.h>
 #include <sys/prctl.h>
 #ifdef HAVE_GETTID
 #define	libspl_gettid()		gettid()
 #else
 #include <sys/syscall.h>
 #define	libspl_gettid()		((pid_t)syscall(__NR_gettid))
 #endif
 #define	libspl_getprogname()	(program_invocation_short_name)
 #define	libspl_getthreadname(buf, len)	\
 	prctl(PR_GET_NAME, (unsigned long)(buf), 0, 0, 0)
-#elif defined(__FreeBSD__)
+#elif defined(__FreeBSD__) || defined(__APPLE__)
+#if !defined(__APPLE__)
 #include <pthread_np.h>
 #define	libspl_gettid()		pthread_getthreadid_np()
+#endif
 #define	libspl_getprogname()	getprogname()
 #define	libspl_getthreadname(buf, len)	\
 	pthread_getname_np(pthread_self(), buf, len);
 #endif
 
 #if defined(HAVE_LIBUNWIND)
 #define	UNW_LOCAL_ONLY
 #include <libunwind.h>
 
 static inline void
 libspl_dump_backtrace(void)
 {
 	unw_context_t uc;
 	unw_cursor_t cp;
 	unw_word_t ip, off;
 	char funcname[128];
 #ifdef HAVE_LIBUNWIND_ELF
 	char objname[128];
 	unw_word_t objoff;
 #endif
 
 	fprintf(stderr, "Call trace:\n");
 	unw_getcontext(&uc);
 	unw_init_local(&cp, &uc);
 	while (unw_step(&cp) > 0) {
 		unw_get_reg(&cp, UNW_REG_IP, &ip);
 		unw_get_proc_name(&cp, funcname, sizeof (funcname), &off);
 #ifdef HAVE_LIBUNWIND_ELF
 		unw_get_elf_filename(&cp, objname, sizeof (objname), &objoff);
 		fprintf(stderr, "  [0x%08lx] %s+0x%2lx (in %s +0x%2lx)\n",
 		    ip, funcname, off, objname, objoff);
 #else
 		fprintf(stderr, "  [0x%08lx] %s+0x%2lx\n", ip, funcname, off);
 #endif
 	}
 }
 #elif defined(HAVE_BACKTRACE)
 #include <execinfo.h>
 
 static inline void
 libspl_dump_backtrace(void)
 {
 	void *btptrs[100];
 	size_t nptrs = backtrace(btptrs, 100);
 	char **bt = backtrace_symbols(btptrs, nptrs);
 	fprintf(stderr, "Call trace:\n");
 	for (size_t i = 0; i < nptrs; i++)
 		fprintf(stderr, "  %s\n", bt[i]);
 	free(bt);
 }
 #else
 #define	libspl_dump_backtrace()
 #endif
 
+#if defined(__APPLE__)
+static inline uint64_t
+libspl_gettid(void)
+{
+	uint64_t tid;
+
+	if (pthread_threadid_np(NULL, &tid) != 0)
+		tid = 0;
+
+	return (tid);
+}
+#endif
+
 static boolean_t libspl_assert_ok = B_FALSE;
 
 void
 libspl_set_assert_ok(boolean_t val)
 {
 	libspl_assert_ok = val;
 }
 
 static pthread_mutex_t assert_lock = PTHREAD_MUTEX_INITIALIZER;
 
 /* printf version of libspl_assert */
 void
 libspl_assertf(const char *file, const char *func, int line,
     const char *format, ...)
 {
 	pthread_mutex_lock(&assert_lock);
 
 	va_list args;
 	char tname[64];
 
 	libspl_getthreadname(tname, sizeof (tname));
 
 	fprintf(stderr, "ASSERT at %s:%d:%s()\n", file, line, func);
 
 	va_start(args, format);
 	vfprintf(stderr, format, args);
 	va_end(args);
 
 	fprintf(stderr, "\n"
 	    "  PID: %-8u  COMM: %s\n"
+#if defined(__APPLE__)
+	    "  TID: %-8" PRIu64 "  NAME: %s\n",
+#else
 	    "  TID: %-8u  NAME: %s\n",
+#endif
 	    getpid(), libspl_getprogname(),
 	    libspl_gettid(), tname);
 
 	libspl_dump_backtrace();
 
 #if !__has_feature(attribute_analyzer_noreturn) && !defined(__COVERITY__)
 	if (libspl_assert_ok) {
 		pthread_mutex_unlock(&assert_lock);
 		return;
 	}
 #endif
 	abort();
 }