diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index 0216b40e3e..54d1908e8b 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -933,7 +933,7 @@ QWindowsWindow::QWindowsWindow(QWindow *aWindow, const QWindowsWindowData &data)
             setFlag(OpenGL_ES2);
     }
 #endif // QT_NO_OPENGL
-    updateDropSite();
+    updateDropSite(window()->isTopLevel());
 
 #ifndef Q_OS_WINCE
     if ((QWindowsContext::instance()->systemInfo() & QWindowsContext::SI_SupportsTouch)
@@ -1020,10 +1020,10 @@ void QWindowsWindow::destroyWindow()
     }
 }
 
-void QWindowsWindow::updateDropSite()
+void QWindowsWindow::updateDropSite(bool topLevel)
 {
     bool enabled = false;
-    if (window()->isTopLevel()) {
+    if (topLevel) {
         switch (window()->type()) {
         case Qt::Window:
         case Qt::Dialog:
@@ -1306,7 +1306,7 @@ void QWindowsWindow::setParent_sys(const QPlatformWindow *parent)
         if (wasTopLevel != isTopLevel) {
             setDropSiteEnabled(false);
             setWindowFlags_sys(window()->flags(), unsigned(isTopLevel ? WindowCreationData::ForceTopLevel : WindowCreationData::ForceChild));
-            updateDropSite();
+            updateDropSite(isTopLevel);
         }
     }
 }
@@ -1561,7 +1561,7 @@ void QWindowsWindow::setWindowFlags(Qt::WindowFlags flags)
         m_data.flags = flags;
         if (m_data.hwnd) {
             m_data = setWindowFlags_sys(flags);
-            updateDropSite();
+            updateDropSite(window()->isTopLevel());
         }
     }
     // When switching to a frameless window, geometry
diff --git a/src/plugins/platforms/windows/qwindowswindow.h b/src/plugins/platforms/windows/qwindowswindow.h
index 6d6d473ccd..0b42e77ecd 100644
--- a/src/plugins/platforms/windows/qwindowswindow.h
+++ b/src/plugins/platforms/windows/qwindowswindow.h
@@ -274,7 +274,7 @@ private:
     void destroyWindow();
     inline bool isDropSiteEnabled() const { return m_dropTarget != 0; }
     void setDropSiteEnabled(bool enabled);
-    void updateDropSite();
+    void updateDropSite(bool topLevel);
     void handleGeometryChange();
     void handleWindowStateChange(Qt::WindowState state);
     inline void destroyIcon();