diff --git a/src/scenedit/scen.undo.hpp b/src/scenedit/scen.undo.hpp
index 5c3190e3..c2c3a75c 100644
--- a/src/scenedit/scen.undo.hpp
+++ b/src/scenedit/scen.undo.hpp
@@ -63,6 +63,7 @@ public:
 	aDrawTerrain(std::string name, stroke_ter_changes_t stroke_changes) :
 		cTerrainAction(name, stroke_changes.begin()->first), // Use arbitrary changed tile as site of change
 		changes(stroke_changes) {}
+	// TODO store another boost::optional action that happens at the same as placing town entrance, sign
 	bool undo_me() override;
 	bool redo_me() override;
 private: