diff --git a/src/runtime/cgo/gcc_darwin_amd64.c b/src/runtime/cgo/gcc_darwin_amd64.c
index d5b7fd8fd8..955b81da0b 100644
--- a/src/runtime/cgo/gcc_darwin_amd64.c
+++ b/src/runtime/cgo/gcc_darwin_amd64.c
@@ -14,15 +14,12 @@ static void (*setg_gcc)(void*);
 void
 x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
 {
-	pthread_attr_t attr;
 	size_t size;
 
 	setg_gcc = setg;
 
-	pthread_attr_init(&attr);
-	pthread_attr_getstacksize(&attr, &size);
-	g->stacklo = (uintptr)&attr - size + 4096;
-	pthread_attr_destroy(&attr);
+	size = pthread_get_stacksize_np(pthread_self());
+	g->stacklo = (uintptr)&size - size + 4096;
 }
 
 
@@ -38,8 +35,9 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	sigfillset(&ign);
 	pthread_sigmask(SIG_SETMASK, &ign, &oset);
 
+	size = pthread_get_stacksize_np(pthread_self());
 	pthread_attr_init(&attr);
-	pthread_attr_getstacksize(&attr, &size);
+	pthread_attr_setstacksize(&attr, size);
 	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
 	ts->g->stackhi = size;
 	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
diff --git a/src/runtime/cgo/gcc_darwin_arm64.c b/src/runtime/cgo/gcc_darwin_arm64.c
index 24be6758d9..5b77a4294a 100644
--- a/src/runtime/cgo/gcc_darwin_arm64.c
+++ b/src/runtime/cgo/gcc_darwin_arm64.c
@@ -36,8 +36,9 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	sigfillset(&ign);
 	pthread_sigmask(SIG_SETMASK, &ign, &oset);
 
+	size = pthread_get_stacksize_np(pthread_self());
 	pthread_attr_init(&attr);
-	pthread_attr_getstacksize(&attr, &size);
+	pthread_attr_setstacksize(&attr, size);
 	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
 	ts->g->stackhi = size;
 	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
@@ -126,15 +127,12 @@ init_working_dir()
 void
 x_cgo_init(G *g, void (*setg)(void*))
 {
-	pthread_attr_t attr;
 	size_t size;
 
 	//fprintf(stderr, "x_cgo_init = %p\n", &x_cgo_init); // aid debugging in presence of ASLR
 	setg_gcc = setg;
-	pthread_attr_init(&attr);
-	pthread_attr_getstacksize(&attr, &size);
-	g->stacklo = (uintptr)&attr - size + 4096;
-	pthread_attr_destroy(&attr);
+	size = pthread_get_stacksize_np(pthread_self());
+	g->stacklo = (uintptr)&size - size + 4096;
 
 #if TARGET_OS_IPHONE
 	darwin_arm_init_mach_exception_handler();