diff --git a/src/plugins/platforms/cocoa/qcocoaeventdispatcher.h b/src/plugins/platforms/cocoa/qcocoaeventdispatcher.h
index 69587a24be..b8d2532b8e 100644
--- a/src/plugins/platforms/cocoa/qcocoaeventdispatcher.h
+++ b/src/plugins/platforms/cocoa/qcocoaeventdispatcher.h
@@ -186,6 +186,7 @@ public:
     QAtomicInt serialNumber;
     int lastSerial;
     bool interrupt;
+    bool propagateInterrupt = false;
 
     static void postedEventsSourceCallback(void *info);
     static void waitingObserverCallback(CFRunLoopObserverRef observer,
diff --git a/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm b/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm
index 110c82bf1f..94b9e62eab 100644
--- a/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm
+++ b/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm
@@ -84,13 +84,12 @@
 #include "private/qthread_p.h"
 #include "private/qguiapplication_p.h"
 #include <qdebug.h>
+#include <qscopeguard.h>
 
 #include <AppKit/AppKit.h>
 
 QT_BEGIN_NAMESPACE
 
-QT_USE_NAMESPACE
-
 static inline CFRunLoopRef mainRunLoop()
 {
     return CFRunLoopGetMain();
@@ -348,6 +347,16 @@ static inline void qt_mac_waitForMoreEvents(NSString *runLoopMode = NSDefaultRun
 bool QCocoaEventDispatcher::processEvents(QEventLoop::ProcessEventsFlags flags)
 {
     Q_D(QCocoaEventDispatcher);
+
+    // In rare rather corner cases a user's application messes with
+    // QEventLoop::exec()/exit() and QCoreApplication::processEvents(),
+    // we have to undo what bool blocker normally does.
+    d->propagateInterrupt = false;
+    const auto boolBlockerUndo = qScopeGuard([d](){
+        if (d->propagateInterrupt)
+            d->interrupt = true;
+        d->propagateInterrupt = false;
+    });
     QBoolBlocker interruptBlocker(d->interrupt, false);
 
     bool interruptLater = false;
@@ -496,7 +505,16 @@ bool QCocoaEventDispatcher::processEvents(QEventLoop::ProcessEventsFlags flags)
 
             if ((d->processEventsFlags & QEventLoop::EventLoopExec) == 0) {
                 // When called "manually", always process posted events and timers
+                bool oldInterrupt = d->interrupt;
                 d->processPostedEvents();
+                if (!oldInterrupt && d->interrupt && !d->currentModalSession()) {
+                    // We had direct processEvent call, coming not from QEventLoop::exec().
+                    // One of the posted events triggered an application to interrupt the loop.
+                    // But bool blocker will reset d->interrupt to false, so the real event
+                    // loop will never notice it was interrupted. Now we'll have to fix it by
+                    // enforcing the value of d->interrupt.
+                    d->propagateInterrupt = true;
+                }
                 retVal = d->processTimers() || retVal;
             }
 
diff --git a/tests/auto/corelib/kernel/qeventdispatcher/tst_qeventdispatcher.cpp b/tests/auto/corelib/kernel/qeventdispatcher/tst_qeventdispatcher.cpp
index 49c10c6a24..365508024b 100644
--- a/tests/auto/corelib/kernel/qeventdispatcher/tst_qeventdispatcher.cpp
+++ b/tests/auto/corelib/kernel/qeventdispatcher/tst_qeventdispatcher.cpp
@@ -67,6 +67,7 @@ private slots:
     void sendPostedEvents_data();
     void sendPostedEvents();
     void processEventsOnlySendsQueuedEvents();
+    void eventLoopExit();
 };
 
 bool tst_QEventDispatcher::event(QEvent *e)
@@ -314,5 +315,49 @@ void tst_QEventDispatcher::processEventsOnlySendsQueuedEvents()
     QCOMPARE(object.eventsReceived, 4);
 }
 
+void tst_QEventDispatcher::eventLoopExit()
+{
+    // This test was inspired by QTBUG-79477. A particular
+    // implementation detail in QCocoaEventDispatcher allowed
+    // QEventLoop::exit() to fail to really exit the event loop.
+    // Thus this test is a part of the dispatcher auto-test.
+
+    // Imitates QApplication::exec():
+    QEventLoop mainLoop;
+    // The test itself is a lambda:
+    QTimer::singleShot(0, [&mainLoop]() {
+        // Two more single shots, both will be posted as events
+        // (zero timeout) and supposed to be processes by the
+        // mainLoop:
+
+        QTimer::singleShot(0, [&mainLoop]() {
+            // wakeUp triggers QCocoaEventDispatcher into incrementing
+            // its 'serialNumber':
+            mainLoop.wakeUp();
+            // QCocoaEventDispatcher::processEvents() will process
+            // posted events and execute the second lambda defined below:
+            QCoreApplication::processEvents();
+        });
+
+        QTimer::singleShot(0, [&mainLoop]() {
+            // With QCocoaEventDispatcher this is executed while in the
+            // processEvents (see above) and would fail to actually
+            // interrupt the loop.
+            mainLoop.exit();
+        });
+    });
+
+    bool timeoutObserved = false;
+    QTimer::singleShot(500, [&timeoutObserved, &mainLoop]() {
+        // In case the QEventLoop::exit above failed, we have to bail out
+        // early, not wasting time:
+        mainLoop.exit();
+        timeoutObserved = true;
+    });
+
+    mainLoop.exec();
+    QVERIFY(!timeoutObserved);
+}
+
 QTEST_MAIN(tst_QEventDispatcher)
 #include "tst_qeventdispatcher.moc"