diff --git a/src/corelib/thread/qthreadpool.cpp b/src/corelib/thread/qthreadpool.cpp
index a8a58fd12a0..bb7e232f42e 100644
--- a/src/corelib/thread/qthreadpool.cpp
+++ b/src/corelib/thread/qthreadpool.cpp
@@ -590,12 +590,14 @@ bool QThreadPool::tryStart(std::function<void()> functionToRun)
 int QThreadPool::expiryTimeout() const
 {
     Q_D(const QThreadPool);
+    QMutexLocker locker(&d->mutex);
     return d->expiryTimeout;
 }
 
 void QThreadPool::setExpiryTimeout(int expiryTimeout)
 {
     Q_D(QThreadPool);
+    QMutexLocker locker(&d->mutex);
     if (d->expiryTimeout == expiryTimeout)
         return;
     d->expiryTimeout = expiryTimeout;
@@ -616,6 +618,7 @@ void QThreadPool::setExpiryTimeout(int expiryTimeout)
 int QThreadPool::maxThreadCount() const
 {
     Q_D(const QThreadPool);
+    QMutexLocker locker(&d->mutex);
     return d->requestedMaxThreadCount;
 }
 
@@ -685,12 +688,14 @@ void QThreadPool::reserveThread()
 void QThreadPool::setStackSize(uint stackSize)
 {
     Q_D(QThreadPool);
+    QMutexLocker locker(&d->mutex);
     d->stackSize = stackSize;
 }
 
 uint QThreadPool::stackSize() const
 {
     Q_D(const QThreadPool);
+    QMutexLocker locker(&d->mutex);
     return d->stackSize;
 }
 
@@ -711,12 +716,14 @@ uint QThreadPool::stackSize() const
 void QThreadPool::setThreadPriority(QThread::Priority priority)
 {
     Q_D(QThreadPool);
+    QMutexLocker locker(&d->mutex);
     d->threadPriority = priority;
 }
 
 QThread::Priority QThreadPool::threadPriority() const
 {
     Q_D(const QThreadPool);
+    QMutexLocker locker(&d->mutex);
     return d->threadPriority;
 }