diff --git a/src/nostalgia/modules/core/src/studio/tilesheeteditor/tilesheeteditormodel.cpp b/src/nostalgia/modules/core/src/studio/tilesheeteditor/tilesheeteditormodel.cpp
index b82a932a..7694efa9 100644
--- a/src/nostalgia/modules/core/src/studio/tilesheeteditor/tilesheeteditormodel.cpp
+++ b/src/nostalgia/modules/core/src/studio/tilesheeteditor/tilesheeteditormodel.cpp
@@ -30,6 +30,17 @@ Palette const TileSheetEditorModel::s_defaultPalette = {
 	.pages = {ox::Vector<Color16>(128)},
 };
 
+// delete pixels of all non-leaf nodes
+static void normalizeSubsheets(TileSheet::SubSheet &ss) noexcept {
+	if (ss.subsheets.empty()) {
+		for (auto &child : ss.subsheets) {
+			normalizeSubsheets(child);
+		}
+	} else {
+		ss.pixels.clear();
+	}
+}
+
 TileSheetEditorModel::TileSheetEditorModel(turbine::Context &ctx, ox::StringView path, studio::UndoStack &undoStack):
 	m_ctx(ctx),
 	m_path(path),
@@ -37,6 +48,7 @@ TileSheetEditorModel::TileSheetEditorModel(turbine::Context &ctx, ox::StringView
 	// ignore failure to load palette
 	m_pal(readObj<Palette>(keelCtx(m_ctx), m_img.defaultPalette).value),
 	m_undoStack(undoStack) {
+	normalizeSubsheets(m_img.subsheet);
 	m_pal.updated.connect(this, &TileSheetEditorModel::markUpdated);
 	m_undoStack.changeTriggered.connect(this, &TileSheetEditorModel::markUpdatedCmdId);
 }