diff --git a/apps/opencs/view/render/worldspacewidget.cpp b/apps/opencs/view/render/worldspacewidget.cpp
index 26c40e3b15..818d91da25 100644
--- a/apps/opencs/view/render/worldspacewidget.cpp
+++ b/apps/opencs/view/render/worldspacewidget.cpp
@@ -204,4 +204,5 @@ void CSVRender::WorldspaceWidget::dropEvent (QDropEvent* event)
 void CSVRender::WorldspaceWidget::elementSelectionChanged()
 {
     setVisibilityMask (getElementMask());
+    flagAsModified();
 }
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