diff --git a/test/testing_darwinunix.c b/test/testing_darwinunix.c
index 239421ea..7fa42b4f 100644
--- a/test/testing_darwinunix.c
+++ b/test/testing_darwinunix.c
@@ -8,6 +8,7 @@
 #include <time.h>
 #include <sys/time.h>
 #include <pthread.h>
+#include <unistd.h>
 #include "testing.h"
 #include "testingpriv.h"
 
@@ -60,12 +61,54 @@ out:
 
 void testingSleep(int64_t nsec)
 {
-	struct timespec duration;
+	struct timespec duration, remaining;
+	void (*prevsig)(int);
+	sigset_t set, prevSet;
+	struct itimerval setiDuration, prevSetiDuration;
+	unsigned sec;
 
-	// TODO check errors, possibly falling back to usleep, setitimer/pause, or even sleep
 	duration.tv_sec = nsec / testingNsecPerSec;
 	duration.tv_nsec = nsec % testingNsecPerSec;
-	nanosleep(&duration, NULL);
+	for (;;) {
+		errno = 0;
+		if (nanosleep(&duration, &remaining) == 0)
+			return;
+		if (errno != EINTR)
+			break;
+		duration = remaining;
+	}
+
+	// if we got here, nanosleep() failed outright
+	if (sigemptyset(&set) != 0)
+		goto fallback;
+	if (sigaddset(&set, SIGABRT) != 0)
+		goto fallback;
+	if (pthread_sigmask(SIG_BLOCK, &set, &prevSet) != 0)
+		goto fallback;
+	prevsig = signal(SIGALRM, SIG_IGN);
+	setiDuration.it_interval.tv_sec = 0;
+	setiDuration.it_interval.tv_usec = 0;
+	// keep using duration for this in case nanosleep() was interrupted before it failed
+	setiDuration.it_value.tv_sec = duration.tv_sec;
+	setiDuration.it_value.tv_usec = duration.tv_nsec / testingNsecPerUsec;
+	if (setitimer(ITIMER_REAL, &setiDuration, &prevSetiDuration) != 0) {
+		pthread_sigmask(SIG_SETMASK, &prevSet, NULL);
+		signal(SIGALRM, prevsig);
+		goto fallback;
+	}
+	// TODO can this return an errno other than EINTR?
+	sigsuspend(&prevSet);
+	setitimer(ITIMER_REAL, &prevSetiDuration, NULL);
+	signal(SIGALRM, prevsig);
+	return;
+
+fallback:
+	// hopefully we never reach this point, because it has the least granularity of all, but there are no errors, so...
+	sec = duration.tv_sec;
+	if (duration.tv_nsec > 0)
+		sec++;
+	while (sec > 0)
+		sec = sleep(sec);
 }
 
 struct testingThread {
@@ -85,21 +128,25 @@ static void *threadThreadProc(void *data)
 testingThread *testingNewThread(void (*f)(void *data), void *data)
 {
 	testingThread *t;
+	int err;
 
 	t = testingprivNew(testingThread);
 	t->f = f;
 	t->data = data;
 
-	// TODO check error
-	pthread_create(&(t->thread), NULL, threadThreadProc, t);
+	err = pthread_create(&(t->thread), NULL, threadThreadProc, t);
+	if (err != 0)
+		testingprivInternalError("error creating thread: %s (%d)", strerror(err), err);
 	return t;
 }
 
 void testingThreadWaitAndFree(testingThread *t)
 {
-	// TODO check errors
-	pthread_join(t->thread, NULL);
-	// TODO end check errors
+	int err;
+
+	err = pthread_join(t->thread, NULL);
+	if (err != 0)
+		testingprivInternalError("error waiting for thread to finish: %s (%d)", strerror(err), err);
 	// TODO do we need to free t->thread somehow?
 	testingprivFree(t);
 }