diff --git a/src/dbus/qdbusintegrator.cpp b/src/dbus/qdbusintegrator.cpp
index a6105d44038..119a354d828 100644
--- a/src/dbus/qdbusintegrator.cpp
+++ b/src/dbus/qdbusintegrator.cpp
@@ -2056,20 +2056,10 @@ QDBusMessage QDBusConnectionPrivate::sendWithReply(const QDBusMessage &message,
     QDBusPendingCallPrivate *pcall = sendWithReplyAsync(message, nullptr, nullptr, nullptr, timeout);
     Q_ASSERT(pcall);
 
-    if (pcall->replyMessage.type() == QDBusMessage::InvalidMessage) {
-        // need to wait for the reply
-        if (mode == QDBus::BlockWithGui) {
-            pcall->watcherHelper = new QDBusPendingCallWatcherHelper;
-            QEventLoop loop;
-            loop.connect(pcall->watcherHelper, &QDBusPendingCallWatcherHelper::reply, &loop, &QEventLoop::quit);
-            loop.connect(pcall->watcherHelper, &QDBusPendingCallWatcherHelper::error, &loop, &QEventLoop::quit);
-
-            // enter the event loop and wait for a reply
-            loop.exec(QEventLoop::ExcludeUserInputEvents | QEventLoop::WaitForMoreEvents);
-        } else {
-            pcall->waitForFinished();
-        }
-    }
+    if (mode == QDBus::BlockWithGui)
+        pcall->waitForFinishedWithGui();
+    else
+        pcall->waitForFinished();
 
     QDBusMessage reply = pcall->replyMessage;
     lastError = QDBusError(reply);      // set or clear error
@@ -2130,6 +2120,7 @@ QDBusPendingCallPrivate *QDBusConnectionPrivate::sendWithReplyAsync(const QDBusM
         pcall->setReplyCallback(receiver, returnMethod);
 
     if (errorMethod) {
+        Q_ASSERT(!pcall->watcherHelper);
         pcall->watcherHelper = new QDBusPendingCallWatcherHelper;
         connect(pcall->watcherHelper, SIGNAL(error(QDBusError,QDBusMessage)), receiver, errorMethod,
                 Qt::QueuedConnection);
diff --git a/src/dbus/qdbuspendingcall.cpp b/src/dbus/qdbuspendingcall.cpp
index 6cbca5ea3a4..f9d414d1bda 100644
--- a/src/dbus/qdbuspendingcall.cpp
+++ b/src/dbus/qdbuspendingcall.cpp
@@ -206,6 +206,26 @@ void QDBusPendingCallPrivate::waitForFinished()
     waitForFinishedCondition.wait(&mutex);
 }
 
+void QDBusPendingCallPrivate::waitForFinishedWithGui()
+{
+    QEventLoop loop;
+
+    {
+        const auto locker = qt_scoped_lock(mutex);
+        if (replyMessage.type() != QDBusMessage::InvalidMessage)
+            return; // already finished
+
+        Q_ASSERT(!watcherHelper);
+        watcherHelper = new QDBusPendingCallWatcherHelper;
+        loop.connect(watcherHelper, &QDBusPendingCallWatcherHelper::reply, &loop,
+                     &QEventLoop::quit);
+        loop.connect(watcherHelper, &QDBusPendingCallWatcherHelper::error, &loop,
+                     &QEventLoop::quit);
+    }
+
+    loop.exec(QEventLoop::ExcludeUserInputEvents | QEventLoop::WaitForMoreEvents);
+}
+
 /*!
     Creates a copy of the \a other pending asynchronous call. Note
     that both objects will refer to the same pending call.
diff --git a/src/dbus/qdbuspendingcall_p.h b/src/dbus/qdbuspendingcall_p.h
index f19acfd0756..2795cc3ecf8 100644
--- a/src/dbus/qdbuspendingcall_p.h
+++ b/src/dbus/qdbuspendingcall_p.h
@@ -68,6 +68,7 @@ public:
     ~QDBusPendingCallPrivate();
     bool setReplyCallback(QObject *target, const char *member);
     void waitForFinished();
+    void waitForFinishedWithGui();
     void setMetaTypes(int count, const QMetaType *types);
     void checkReceivedSignature();
 };