diff --git a/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/darling/emulation/tsd.h b/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/darling/emulation/tsd.h
new file mode 120000
index 000000000..c8d01cfe0
--- /dev/null
+++ b/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/darling/emulation/tsd.h
@@ -0,0 +1 @@
+../../../../../../../../../../src/external/xnu/darling/src/libsystem_kernel/emulation/linux/tsd.h
\ No newline at end of file
diff --git a/src/external/libpthread b/src/external/libpthread
index 1cdf76eab..f07f265bf 160000
--- a/src/external/libpthread
+++ b/src/external/libpthread
@@ -1 +1 @@
-Subproject commit 1cdf76eab5b283fc282dbe605eb632da6e3a6e68
+Subproject commit f07f265bfbcf071c1adfc808de971e053ea5edc5
diff --git a/src/external/xnu b/src/external/xnu
index b2bd57725..99020685f 160000
--- a/src/external/xnu
+++ b/src/external/xnu
@@ -1 +1 @@
-Subproject commit b2bd57725b78e715b6cf396d451ca29a68e77748
+Subproject commit 99020685f14fd3f7a9466fc692f16ecf440f3f39
diff --git a/src/xtrace/tls.cpp b/src/xtrace/tls.cpp
index 980a9ea00..1ccfd97c9 100644
--- a/src/xtrace/tls.cpp
+++ b/src/xtrace/tls.cpp
@@ -27,16 +27,16 @@ struct tls_table {
 };
 
 // since we still need to handle some calls after pthread_terminate is called and libpthread unwinds its TLS right before calling pthread_terminate,
-// we have to use a slightly hackier technique: using one of the system's reserved but unused TLS keys.
-// key 200 seems like a good fit; it's in the reserved region but it's not currently listed in `pthread/tsd_private.h` as being in-use by anything.
+// we have to use a slightly hackier technique: using one of the system's reserved but unused TLS keys; we use one from the range we currently reserve
+// for Darling.
 
-#define __PTK_XTRACE_TLS 200
+#include <darling/emulation/tsd.h>
 
 // TODO: also perform TLS cleanup for other threads when doing a fork
 
 extern "C"
 void xtrace_tls_thread_cleanup(void) {
-	tls_table_t table = (tls_table_t)_pthread_getspecific_direct(__PTK_XTRACE_TLS);
+	tls_table_t table = (tls_table_t)_pthread_getspecific_direct(__PTK_DARLING_XTRACE_TLS);
 	if (!table) {
 		xtrace_tls_debug("no table to cleanup for this thread");
 		return;
@@ -58,7 +58,7 @@ extern "C"
 void* xtrace_tls(void* key, size_t size, bool* created, xtrace_tls_destructor_f destructor) {
 	xtrace_tls_debug("looking up tls variable for key %p", key);
 
-	tls_table_t table = (tls_table_t)_pthread_getspecific_direct(__PTK_XTRACE_TLS);
+	tls_table_t table = (tls_table_t)_pthread_getspecific_direct(__PTK_DARLING_XTRACE_TLS);
 
 	xtrace_tls_debug("got %p as table pointer from pthread", table);
 
@@ -70,7 +70,7 @@ void* xtrace_tls(void* key, size_t size, bool* created, xtrace_tls_destructor_f
 			xtrace_abort("xtrace: failed TLS table memory allocation");
 		}
 		table->size = 0;
-		_pthread_setspecific_direct(__PTK_XTRACE_TLS, table);
+		_pthread_setspecific_direct(__PTK_DARLING_XTRACE_TLS, table);
 	}
 
 	// check if the key is already present