diff --git a/src/gui/painting/qpaintengine_raster.cpp b/src/gui/painting/qpaintengine_raster.cpp
index 6b8136c52d..207e31d91a 100644
--- a/src/gui/painting/qpaintengine_raster.cpp
+++ b/src/gui/painting/qpaintengine_raster.cpp
@@ -3653,8 +3653,9 @@ QImage::Format QRasterBuffer::prepare(QImage *image)
     drawHelper = qDrawHelper + format;
     if (image->depth() == 1 && image->colorTable().size() == 2) {
         monoDestinationWithClut = true;
-        destColor0 = qPremultiply(image->colorTable()[0]);
-        destColor1 = qPremultiply(image->colorTable()[1]);
+        const QVector<QRgb> colorTable = image->colorTable();
+        destColor0 = qPremultiply(colorTable[0]);
+        destColor1 = qPremultiply(colorTable[1]);
     }
 
     return format;