diff --git a/src/corelib/kernel/qcore_unix_p.h b/src/corelib/kernel/qcore_unix_p.h
index 957c646d80..24c2eef399 100644
--- a/src/corelib/kernel/qcore_unix_p.h
+++ b/src/corelib/kernel/qcore_unix_p.h
@@ -312,6 +312,7 @@ static inline pid_t qt_safe_waitpid(pid_t pid, int *status, int options)
 
 // in qelapsedtimer_mac.cpp or qtimestamp_unix.cpp
 timeval qt_gettime() Q_DECL_NOTHROW;
+void qt_nanosleep(timespec amount);
 
 Q_CORE_EXPORT int qt_safe_select(int nfds, fd_set *fdread, fd_set *fdwrite, fd_set *fdexcept,
                                  const struct timeval *tv);
diff --git a/src/corelib/thread/qthread_unix.cpp b/src/corelib/thread/qthread_unix.cpp
index f472dee56e..f6df15f7a7 100644
--- a/src/corelib/thread/qthread_unix.cpp
+++ b/src/corelib/thread/qthread_unix.cpp
@@ -454,59 +454,27 @@ void QThread::yieldCurrentThread()
     sched_yield();
 }
 
-/*
-    \internal
-    helper function to do thread sleeps, since usleep()/nanosleep()
-    aren't reliable enough (in terms of behavior and availability)
-*/
-static void thread_sleep(struct timespec *ti)
+static timespec makeTimespec(time_t secs, long nsecs)
 {
-    pthread_mutex_t mtx;
-    pthread_cond_t cnd;
-
-    pthread_mutex_init(&mtx, 0);
-    pthread_cond_init(&cnd, 0);
-
-    pthread_mutex_lock(&mtx);
-    (void) pthread_cond_timedwait(&cnd, &mtx, ti);
-    pthread_mutex_unlock(&mtx);
-
-    pthread_cond_destroy(&cnd);
-    pthread_mutex_destroy(&mtx);
+    struct timespec ts;
+    ts.tv_sec = secs;
+    ts.tv_nsec = nsecs;
+    return ts;
 }
 
 void QThread::sleep(unsigned long secs)
 {
-    struct timeval tv;
-    gettimeofday(&tv, 0);
-    struct timespec ti;
-    ti.tv_sec = tv.tv_sec + secs;
-    ti.tv_nsec = (tv.tv_usec * 1000);
-    thread_sleep(&ti);
+    qt_nanosleep(makeTimespec(secs, 0));
 }
 
 void QThread::msleep(unsigned long msecs)
 {
-    struct timeval tv;
-    gettimeofday(&tv, 0);
-    struct timespec ti;
-
-    ti.tv_nsec = (tv.tv_usec + (msecs % 1000) * 1000) * 1000;
-    ti.tv_sec = tv.tv_sec + (msecs / 1000) + (ti.tv_nsec / 1000000000);
-    ti.tv_nsec %= 1000000000;
-    thread_sleep(&ti);
+    qt_nanosleep(makeTimespec(msecs / 1000, msecs % 1000 * 1000 * 1000));
 }
 
 void QThread::usleep(unsigned long usecs)
 {
-    struct timeval tv;
-    gettimeofday(&tv, 0);
-    struct timespec ti;
-
-    ti.tv_nsec = (tv.tv_usec + (usecs % 1000000)) * 1000;
-    ti.tv_sec = tv.tv_sec + (usecs / 1000000) + (ti.tv_nsec / 1000000000);
-    ti.tv_nsec %= 1000000000;
-    thread_sleep(&ti);
+    qt_nanosleep(makeTimespec(usecs / 1000 / 1000, usecs % (1000*1000) * 1000));
 }
 
 #ifdef QT_HAS_THREAD_PRIORITY_SCHEDULING
diff --git a/src/corelib/tools/qelapsedtimer_mac.cpp b/src/corelib/tools/qelapsedtimer_mac.cpp
index 2aeaaa60f0..0304c68226 100644
--- a/src/corelib/tools/qelapsedtimer_mac.cpp
+++ b/src/corelib/tools/qelapsedtimer_mac.cpp
@@ -39,8 +39,12 @@
 **
 ****************************************************************************/
 
+// ask for the latest POSIX, just in case
+#define _POSIX_C_SOURCE 200809L
+
 #include "qelapsedtimer.h"
 #include <sys/time.h>
+#include <time.h>
 #include <unistd.h>
 
 #include <mach/mach_time.h>
@@ -83,6 +87,15 @@ timeval qt_gettime() Q_DECL_NOTHROW
     return tv;
 }
 
+void qt_nanosleep(timespec amount)
+{
+    // Mac doesn't have clock_nanosleep, but it does have nanosleep.
+    // nanosleep is POSIX.1-1993
+
+    int r;
+    EINTR_LOOP(r, nanosleep(&amount, &amount));
+}
+
 void QElapsedTimer::start() Q_DECL_NOTHROW
 {
     t1 = mach_absolute_time();
diff --git a/src/corelib/tools/qelapsedtimer_unix.cpp b/src/corelib/tools/qelapsedtimer_unix.cpp
index d7419aea18..435a797a4d 100644
--- a/src/corelib/tools/qelapsedtimer_unix.cpp
+++ b/src/corelib/tools/qelapsedtimer_unix.cpp
@@ -144,6 +144,20 @@ timeval qt_gettime() Q_DECL_NOTHROW
     return tv;
 }
 
+void qt_nanosleep(timespec amount)
+{
+    // We'd like to use clock_nanosleep.
+    //
+    // But clock_nanosleep is from POSIX.1-2001 and both are *not*
+    // affected by clock changes when using relative sleeps, even for
+    // CLOCK_REALTIME.
+    //
+    // nanosleep is POSIX.1-1993
+
+    int r;
+    EINTR_LOOP(r, nanosleep(&amount, &amount));
+}
+
 static qint64 elapsedAndRestart(qint64 sec, qint64 frac,
                                 qint64 *nowsec, qint64 *nowfrac)
 {