diff --git a/src/plugins/platforms/xcb/nativepainting/qbackingstore_x11.cpp b/src/plugins/platforms/xcb/nativepainting/qbackingstore_x11.cpp
index 8851ea59e50..ed482e5daee 100644
--- a/src/plugins/platforms/xcb/nativepainting/qbackingstore_x11.cpp
+++ b/src/plugins/platforms/xcb/nativepainting/qbackingstore_x11.cpp
@@ -62,8 +62,10 @@ QXcbNativeBackingStore::QXcbNativeBackingStore(QWindow *window)
     : QPlatformBackingStore(window)
     , m_translucentBackground(false)
 {
-    if (QXcbWindow *w = static_cast<QXcbWindow *>(window->handle()))
-        m_translucentBackground = w->connection()->hasXRender() && QImage::toPixelFormat(w->imageFormat()).alphaSize() > 0;
+    if (QXcbWindow *w = static_cast<QXcbWindow *>(window->handle())) {
+        m_translucentBackground = w->connection()->hasXRender() &&
+            QImage::toPixelFormat(w->imageFormat()).alphaUsage() == QPixelFormat::UsesAlpha;
+    }
 }
 
 QXcbNativeBackingStore::~QXcbNativeBackingStore()