diff --git a/src/tree_gui.cpp b/src/tree_gui.cpp
--- a/src/tree_gui.cpp
+++ b/src/tree_gui.cpp
@@ -133,7 +133,7 @@ public:
 	virtual void OnPlaceMouseUp(ViewportPlaceMethod select_method, ViewportDragDropSelectionProcess select_proc, Point pt, TileIndex start_tile, TileIndex end_tile)
 	{
 		if (pt.x != -1 && select_proc == DDSP_PLANT_TREES) {
-			DoCommandP(end_tile, this->tree_to_plant, start_tile, NULL,
+			DoCommandP(end_tile, this->tree_to_plant, start_tile,
 				CMD_PLANT_TREE | CMD_MSG(STR_2805_CAN_T_PLANT_TREE_HERE));
 		}
 	}