diff --git a/src/water_cmd.cpp b/src/water_cmd.cpp
index 8325c4da19..50d105dbc9 100644
--- a/src/water_cmd.cpp
+++ b/src/water_cmd.cpp
@@ -360,6 +360,8 @@ static CommandCost DoBuildLock(TileIndex tile, DiagDirection dir, DoCommandFlag
 		MarkTileDirtyByTile(tile + delta);
 		MarkCanalsAndRiversAroundDirty(tile - delta);
 		MarkCanalsAndRiversAroundDirty(tile + delta);
+		InvalidateWaterRegion(tile - delta);
+		InvalidateWaterRegion(tile + delta);
 	}
 	cost.AddCost(_price[PR_BUILD_LOCK]);