diff --git a/src/gui/kernel/qplatformsurface.cpp b/src/gui/kernel/qplatformsurface.cpp
index fdb2cf567d..772207a7a9 100644
--- a/src/gui/kernel/qplatformsurface.cpp
+++ b/src/gui/kernel/qplatformsurface.cpp
@@ -68,6 +68,17 @@ QPlatformSurface::QPlatformSurface(QSurface *surface) : m_surface(surface)
 {
 }
 
+bool QPlatformSurface::isRasterSurface(QSurface *surface)
+{
+    switch (surface->surfaceType()) {
+    case QSurface::RasterSurface:
+    case QSurface::RasterGLSurface:
+        return true;
+    default:
+        return false;
+    };
+}
+
 #ifndef QT_NO_DEBUG_STREAM
 Q_GUI_EXPORT QDebug operator<<(QDebug debug, const QPlatformSurface *surface)
 {
diff --git a/src/gui/kernel/qplatformsurface.h b/src/gui/kernel/qplatformsurface.h
index 475f3ef330..bf0ba81d7f 100644
--- a/src/gui/kernel/qplatformsurface.h
+++ b/src/gui/kernel/qplatformsurface.h
@@ -73,6 +73,8 @@ public:
     QSurface *surface() const;
     virtual QPlatformScreen *screen() const = 0;
 
+    static bool isRasterSurface(QSurface *surface);
+
 private:
     explicit QPlatformSurface(QSurface *surface);
 
diff --git a/src/gui/painting/qbackingstore.cpp b/src/gui/painting/qbackingstore.cpp
index a2e5f7286e..f76b9864fc 100644
--- a/src/gui/painting/qbackingstore.cpp
+++ b/src/gui/painting/qbackingstore.cpp
@@ -192,17 +192,6 @@ void QBackingStore::endPaint()
     handle()->endPaint();
 }
 
-static bool isRasterSurface(QWindow *window)
-{
-    switch (window->surfaceType()) {
-    case QSurface::RasterSurface:
-    case QSurface::RasterGLSurface:
-        return true;
-    default:
-        return false;
-    };
-}
-
 /*!
     Flushes the given \a region from the specified \a window onto the
     screen.
@@ -229,7 +218,7 @@ void QBackingStore::flush(const QRegion &region, QWindow *window, const QPoint &
         return;
     }
 
-    if (!isRasterSurface(window)) {
+    if (!QPlatformSurface::isRasterSurface(window)) {
         qWarning() << "Attempted flush to non-raster surface" << window << "of type" << window->surfaceType()
             << (window->inherits("QWidgetWindow") ? "(consider using Qt::WA_PaintOnScreen to exclude "
                                                    "from backingstore sync)" : "");
diff --git a/src/gui/painting/qrasterbackingstore.cpp b/src/gui/painting/qrasterbackingstore.cpp
index a3ffe11d19..49dbeae774 100644
--- a/src/gui/painting/qrasterbackingstore.cpp
+++ b/src/gui/painting/qrasterbackingstore.cpp
@@ -82,7 +82,7 @@ QImage QRasterBackingStore::toImage() const
 
 bool QRasterBackingStore::scroll(const QRegion &region, int dx, int dy)
 {
-    if (window()->surfaceType() != QSurface::RasterSurface)
+    if (!QPlatformSurface::isRasterSurface(window()))
         return false;
 
     extern void qt_scrollRectInImage(QImage &, const QRect &, const QPoint &);