diff --git a/src/landscape.cpp b/src/landscape.cpp
--- a/src/landscape.cpp
+++ b/src/landscape.cpp
@@ -638,7 +638,7 @@ CommandCost CmdClearArea(TileIndex tile,
 
 	for (int x = sx; x <= ex; ++x) {
 		for (int y = sy; y <= ey; ++y) {
-			SmallVector<TileArea, 1> object_areas = _cleared_object_areas;
+			SmallVector<TileArea, 1> object_areas(_cleared_object_areas);
 			CommandCost ret = DoCommand(TileXY(x, y), 0, 0, flags & ~DC_EXEC, CMD_LANDSCAPE_CLEAR);
 			_cleared_object_areas = object_areas;
 			if (ret.Failed()) {