diff --git a/src/viewport.cpp b/src/viewport.cpp
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -462,10 +462,10 @@ Point GetTileZoomCenterWindow(bool in, W
 void HandleZoomMessage(Window *w, const ViewPort *vp, byte widget_zoom_in, byte widget_zoom_out)
 {
 	w->SetWidgetDisabledState(widget_zoom_in, vp->zoom == ZOOM_LVL_MIN);
-	w->InvalidateWidget(widget_zoom_in);
+	w->SetWidgetDirty(widget_zoom_in);
 
 	w->SetWidgetDisabledState(widget_zoom_out, vp->zoom == ZOOM_LVL_MAX);
-	w->InvalidateWidget(widget_zoom_out);
+	w->SetWidgetDirty(widget_zoom_out);
 }
 
 /**