diff --git a/src/corelib/kernel/qcoreevent.cpp b/src/corelib/kernel/qcoreevent.cpp
index 46398872f7..838c90fce7 100644
--- a/src/corelib/kernel/qcoreevent.cpp
+++ b/src/corelib/kernel/qcoreevent.cpp
@@ -433,8 +433,9 @@ struct QBasicAtomicBitField {
         QBasicAtomicInteger<uint> &entry = data[which / BitsPerInt];
         const uint old = entry.loadRelaxed();
         const uint bit = 1U << (which % BitsPerInt);
-        return !(old & bit) // wasn't taken
-            && entry.testAndSetRelaxed(old, old | bit); // still wasn't taken
+        if (old & bit)
+            return false;       // already taken
+        return (entry.fetchAndOrRelaxed(bit) & bit) == 0;
 
         // don't update 'next' here - it's unlikely that it will need
         // to be updated, in the general case, and having 'next'
diff --git a/src/corelib/kernel/qeventdispatcher_unix.cpp b/src/corelib/kernel/qeventdispatcher_unix.cpp
index dc87a9cd63..12603d77f0 100644
--- a/src/corelib/kernel/qeventdispatcher_unix.cpp
+++ b/src/corelib/kernel/qeventdispatcher_unix.cpp
@@ -123,7 +123,7 @@ pollfd QThreadPipe::prepare() const
 
 void QThreadPipe::wakeUp()
 {
-    if (wakeUps.testAndSetAcquire(0, 1)) {
+    if ((wakeUps.fetchAndOrAcquire(1) & 1) == 0) {
 #if QT_CONFIG(eventfd)
         eventfd_write(fds[0], 1);
         return;