From 50fb460203b52a93f1892d8c35955087d11193b4 Mon Sep 17 00:00:00 2001
From: peter1138 <peter1138@openttd.org>
Date: Mon, 5 Mar 2018 22:57:49 +0000
Subject: [PATCH] (svn r27973) -Fix: [FS#6662] Avoid tile operations outside
 map border when building lock.

---
 src/water_cmd.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/water_cmd.cpp b/src/water_cmd.cpp
index edce4cda58..6b11e7e64b 100644
--- a/src/water_cmd.cpp
+++ b/src/water_cmd.cpp
@@ -73,7 +73,7 @@ static const uint8 _flood_from_dirs[] = {
  */
 static inline void MarkTileDirtyIfCanalOrRiver(TileIndex tile)
 {
-	if (IsTileType(tile, MP_WATER) && (IsCanal(tile) || IsRiver(tile))) MarkTileDirtyByTile(tile);
+	if (IsValidTile(tile) && IsTileType(tile, MP_WATER) && (IsCanal(tile) || IsRiver(tile))) MarkTileDirtyByTile(tile);
 }
 
 /**