diff -r a5fdea13a991 -r d7bd32dc6c59 src/ai/api/ai_tile.cpp
--- a/src/ai/api/ai_tile.cpp	Mon Feb 11 18:08:09 2008 +0000
+++ b/src/ai/api/ai_tile.cpp	Fri Feb 15 23:31:51 2008 +0000
@@ -16,13 +16,13 @@
 	if (tile >= ::MapSize()) return false;
 
 	switch (::GetTileType(tile)) {
-		default: return 1;
+		default: return true;
 		case MP_VOID:
 		case MP_HOUSE:
 		case MP_STATION:
 		case MP_INDUSTRY:
 		case MP_UNMOVABLE:
-		case MP_WATER: return 0;
+		case MP_WATER: return false;
 	}
 }
 
@@ -53,7 +53,7 @@
 int32 AITile::GetCargoAcceptance(TileIndex tile, CargoID cargo_type, uint width, uint height, uint rad)
 {
 	/* Outside of the map */
-	if (tile >= ::MapSize()) return false;
+	if (tile >= ::MapSize()) return 0;
 
 	AcceptedCargo accepts;
 	GetAcceptanceAroundTiles(accepts, tile, width, height, _patches.modified_catchment ? rad : 4);
@@ -63,7 +63,7 @@
 bool AITile::RaiseTile(TileIndex tile, int32 slope)
 {
 	/* Outside of the map */
-	if (tile >= ::MapSize()) return 0;
+	if (tile >= ::MapSize()) return false;
 
 	return this->DoCommand(tile, slope, 1, CMD_TERRAFORM_LAND);
 }
@@ -71,7 +71,7 @@
 bool AITile::LowerTile(TileIndex tile, int32 slope)
 {
 	/* Outside of the map */
-	if (tile >= ::MapSize()) return 0;
+	if (tile >= ::MapSize()) return false;
 
 	return this->DoCommand(tile, slope, 0, CMD_TERRAFORM_LAND);
 }