diff --git a/src/town_cmd.cpp b/src/town_cmd.cpp
--- a/src/town_cmd.cpp
+++ b/src/town_cmd.cpp
@@ -3457,7 +3457,7 @@ Town *ClosestTownFromTile(TileIndex tile
 }
 
 static bool _town_rating_test = false; ///< If \c true, town rating is in test-mode.
-static SmallMap<const Town *, int, 4> _town_test_ratings; ///< Map of towns to modified ratings, while in town rating test-mode.
+static SmallMap<const Town *, int> _town_test_ratings; ///< Map of towns to modified ratings, while in town rating test-mode.
 
 /**
  * Switch the town rating to test-mode, to allow commands to be tested without affecting current ratings.