diff --git a/ttd.h b/ttd.h
--- a/ttd.h
+++ b/ttd.h
@@ -469,9 +469,10 @@ enum Sprites {
 };
 
 enum MAP_OWNERS {
-	OWNER_TOWN = 0xf, // a town owns the tile
-	OWNER_NONE = 0x10,// nobody owns the tile
-	OWNER_WATER= 0x11,// "water" owns the tile
+	OWNER_TOWN			= 0xf, // a town owns the tile
+	OWNER_NONE			= 0x10,// nobody owns the tile
+	OWNER_WATER			= 0x11,// "water" owns the tile
+	OWNER_SPECTATOR	= 0xff, // spectator in MP or in scenario editor
 };
 
 VARDEF bool _savegame_sort_dirty;