diff --git a/samples/qt/VoxelDemo/inc/VoxelClient_VisDrawer.h b/samples/qt/VoxelDemo/inc/VoxelClient_VisDrawer.h
index b94f92b559..a2f0e6e2cb 100644
--- a/samples/qt/VoxelDemo/inc/VoxelClient_VisDrawer.h
+++ b/samples/qt/VoxelDemo/inc/VoxelClient_VisDrawer.h
@@ -19,7 +19,7 @@
 #include "Voxel_VisData.h"
 #include <Graphic3d_BndBox4f.hxx>
 
-class Handle(OpenGl_GraphicDriver);
+#include <OpenGl_GraphicDriver.hxx>
 
 class VoxelClient_VisDrawer
 {