diff --git a/framelesshelper.cpp b/framelesshelper.cpp
index 26b1433..11709ed 100644
--- a/framelesshelper.cpp
+++ b/framelesshelper.cpp
@@ -99,7 +99,7 @@ void FramelessHelper::updateQtFrame(QWindow *window, const int titleBarHeight)
                                     marginsVar);
         }
 #else
-        auto *platformWindow = dynamic_cast<QPlatformInterface::Private::QWindowsWindow *>(
+        auto *platformWindow = qobject_cast<QNativeInterface::Private::QWindowsWindow *>(
             window->handle());
         if (platformWindow) {
             platformWindow->setCustomMargins(margins);
diff --git a/winnativeeventfilter.cpp b/winnativeeventfilter.cpp
index 043fe0e..24914be 100644
--- a/winnativeeventfilter.cpp
+++ b/winnativeeventfilter.cpp
@@ -1951,7 +1951,7 @@ void WinNativeEventFilter::updateQtFrame(QWindow *window, const int titleBarHeig
                                     marginsVar);
         }
 #else
-        auto *platformWindow = dynamic_cast<QPlatformInterface::Private::QWindowsWindow *>(
+        auto *platformWindow = qobject_cast<QNativeInterface::Private::QWindowsWindow *>(
             window->handle());
         if (platformWindow) {
             platformWindow->setCustomMargins(margins);