diff --git a/test/testing_darwin.c b/test/testing_darwin.c
deleted file mode 100644
index bf67b44a..00000000
--- a/test/testing_darwin.c
+++ /dev/null
@@ -1,43 +0,0 @@
-// 22 april 2019
-#include <stdlib.h>
-#include <string.h>
-#include <mach/mach.h>
-#include <mach/mach_time.h>
-#include "testing.h"
-#include "testingpriv.h"
-
-struct testingTimer {
-	uint64_t start;
-	uint64_t end;
-};
-
-testingTimer *testingNewTimer(void)
-{
-	return testingprivNew(testingTimer);
-}
-
-void testingFreeTimer(testingTimer *t)
-{
-	testingprivFree(t);
-}
-
-void testingTimerStart(testingTimer *t)
-{
-	t->start = mach_absolute_time();
-}
-
-void testingTimerEnd(testingTimer *t)
-{
-	t->end = mach_absolute_time();
-}
-
-int64_t testingTimerNsec(testingTimer *t)
-{
-	mach_timebase_info_data_t mt;
-	uint64_t c;
-
-	mach_timebase_info(&mt);
-	c = t->end - t->start;
-	c = c * mt.numer / mt.denom;
-	return (int64_t) c;
-}
diff --git a/test/testing_unix.c b/test/testing_unix.c
deleted file mode 100644
index a6719b88..00000000
--- a/test/testing_unix.c
+++ /dev/null
@@ -1,46 +0,0 @@
-// 23 april 2019
-#define _POSIX_C_SOURCE 200112L
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>
-#include "testing.h"
-#include "testingpriv.h"
-
-struct testingTimer {
-	struct timespec start;
-	struct timespec end;
-};
-
-testingTimer *testingNewTimer(void)
-{
-	return testingprivNew(testingTimer);
-}
-
-void testingFreeTimer(testingTimer *t)
-{
-	testingprivFree(t);
-}
-
-void testingTimerStart(testingTimer *t)
-{
-	// TODO check errors
-	clock_gettime(CLOCK_MONOTONIC, &(t->start));
-}
-
-void testingTimerEnd(testingTimer *t)
-{
-	// TODO check errors
-	clock_gettime(CLOCK_MONOTONIC, &(t->end));
-}
-
-// TODO replace with proper subtraction code
-int64_t testingTimerNsec(testingTimer *t)
-{
-	int64_t nstart, nend;
-
-	nstart = ((int64_t) (t->start.tv_sec)) * testingNsecPerSec;
-	nstart += t->start.tv_nsec;
-	nend = ((int64_t) (t->end.tv_sec)) * testingNsecPerSec;
-	nend += t->end.tv_nsec;
-	return nend - nstart;
-}
diff --git a/test/timer_darwinunix.c b/test/timer_darwinunix.c
new file mode 100644
index 00000000..b35c088b
--- /dev/null
+++ b/test/timer_darwinunix.c
@@ -0,0 +1,83 @@
+// 3 may 2019
+#ifdef __APPLE__
+#include <mach/mach.h>
+#include <mach/mach_time.h>
+#else
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#endif
+#include "timer.h"
+
+#ifdef __APPLE__
+
+timerTime timerMonotonicNow(void)
+{
+	return (timerTime) mach_absolute_time();
+}
+
+timerDuration timerTimeSub(timerTime end, timerTime start)
+{
+	mach_timebase_info_data_t mt;
+	timerTime c;
+	timerDuration ret;
+
+	mach_timebase_info(&mt);
+	c = end - start;
+	ret = ((timerDuration) c) * mt.numer / mt.denom;
+	return ret;
+}
+
+#else
+
+static void mustclock_gettime(clockid_t id, struct timespec *ts)
+{
+	int err;
+
+	errno = 0;
+	if (clock_gettime(id, ts) != 0) {
+		err = errno;
+		fprintf(stderr, "*** internal error in timerMonotonicNow(): clock_gettime() failed: %s (%d)\n", strerror(err), err);
+		abort();
+	}
+}
+
+static struct timespec base;
+static pthread_once_t baseOnce = PTHREAD_ONCE_INIT;
+
+static void baseInit(void)
+{
+	mustclock_gettime(CLOCK_MONOTONIC, &base);
+}
+
+timerTime timerMonotonicNow(void)
+{
+	struct timespec ts;
+	timerTIme ret;
+	int err;
+
+	err = pthread_once(&baseOnce, baseInit);
+	if (err != 0) {
+		fprintf(stderr, "*** internal error in timerMonotonicNow(): pthread_once() failed: %s (%d)\n", strerror(err), err);
+		abort();
+	}
+	mustclock_gettime(CLOCK_MONOTONIC, &ts);
+	ts.tv_sec -= base.tv_sec;
+	ts.tv_nsec -= base.tv_nsec;
+	if (ts.tv_nsec < 0) {		// this is safe because POSIX requires this to be of type long
+		ts.tv_sec--;
+		ts.tv_nsec += (long) timerSecond;
+	}
+	ret = ((timerTime) (ts.tv_sec)) * timerSecond;
+	ret += (timerTime) (ts.tv_nsec);
+	return ret;
+}
+
+timerDuration timerTimeSub(timerTime end, timerTime start)
+{
+	return end - start;
+}
+
+#endif