diff --git a/plugins/platforms/x11/windowed/egl_x11_backend.cpp b/plugins/platforms/x11/windowed/egl_x11_backend.cpp
--- a/plugins/platforms/x11/windowed/egl_x11_backend.cpp
+++ b/plugins/platforms/x11/windowed/egl_x11_backend.cpp
@@ -106,7 +106,9 @@
     const QSize &overall = screens()->size();
     const QRect &v = screens()->geometry(screenId);
     // TODO: are the values correct?
-    glViewport(-v.x(), v.height() - overall.height() - v.y(), overall.width(), overall.height());
+
+    qreal scale = screens()->scale(screenId);
+    glViewport(-v.x(), v.height() - overall.height() - v.y(), overall.width() * scale, overall.height() * scale);
 }
 
 void EglX11Backend::endRenderingFrameForScreen(int screenId, const QRegion &renderedRegion, const QRegion &damagedRegion)
diff --git a/plugins/platforms/x11/windowed/x11windowed_backend.cpp b/plugins/platforms/x11/windowed/x11windowed_backend.cpp
--- a/plugins/platforms/x11/windowed/x11windowed_backend.cpp
+++ b/plugins/platforms/x11/windowed/x11windowed_backend.cpp
@@ -471,7 +471,7 @@
 {
     QVector<QRect> ret;
     for (auto it = m_windows.constBegin(); it != m_windows.constEnd(); ++it) {
-        ret << QRect((*it).internalPosition, (*it).size);
+        ret << QRect((*it).internalPosition, (*it).size / (*it).scale);
     }
     return ret;
 }