first.patch

diff --git i/src/corelib/kernel/qcoreapplication.cpp w/src/corelib/kernel/qcoreapplication.cpp
index 553eaf0..247d2ad 100644
--- i/src/corelib/kernel/qcoreapplication.cpp
+++ w/src/corelib/kernel/qcoreapplication.cpp
@@ -144,8 +144,13 @@ QString QCoreApplicationPrivate::macMenuBarName()
     return bundleName;
 }
 #endif
+
+static QBasicMutex appNameMutex;
+
 QString QCoreApplicationPrivate::appName() const
 {
+    QMutexLocker locker(&appNameMutex);
+
     if (applicationName.isNull()) {
 #ifdef Q_OS_MAC
         applicationName = macMenuBarName();

second.patch

diff --git i/src/corelib/kernel/qcoreapplication.cpp w/src/corelib/kernel/qcoreapplication.cpp
index 553eaf0..52416ae 100644
--- i/src/corelib/kernel/qcoreapplication.cpp
+++ w/src/corelib/kernel/qcoreapplication.cpp
@@ -146,6 +146,9 @@ QString QCoreApplicationPrivate::macMenuBarName()
 #endif
 QString QCoreApplicationPrivate::appName() const
 {
+    static QBasicMutex appNameMutex;
+    QMutexLocker locker(&appNameMutex);
+
     if (applicationName.isNull()) {
 #ifdef Q_OS_MAC
         applicationName = macMenuBarName();