diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index 4be133e277..93e6131ab9 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -1009,6 +1009,8 @@ void QDockWidgetPrivate::setWindowState(bool floating, bool unplug, const QRect
     }
 
     bool wasFloating = q->isFloating();
+    if (wasFloating) // Prevent repetitive unplugging from nested invocations (QTBUG-42818)
+        unplug = false;
     bool hidden = q->isHidden();
 
     if (q->isVisible())