diff --git a/src/newgrf_house.cpp b/src/newgrf_house.cpp
index d267ff1f26..779f6cd3f1 100644
--- a/src/newgrf_house.cpp
+++ b/src/newgrf_house.cpp
@@ -365,7 +365,7 @@ static const SpriteGroup *HouseResolveReal(const ResolverObject *object, const R
  *
  * Returns a resolver object to be used with feature 07 spritegroups.
  */
-static void NewHouseResolver(ResolverObject *res, HouseID house_id, TileIndex tile, const Town *town)
+static void NewHouseResolver(ResolverObject *res, HouseID house_id, TileIndex tile, Town *town)
 {
 	res->GetRandomBits = HouseGetRandomBits;
 	res->GetTriggers   = HouseGetTriggers;
@@ -390,7 +390,7 @@ static void NewHouseResolver(ResolverObject *res, HouseID house_id, TileIndex ti
 	res->grffile         = (hs != NULL ? hs->grf_prop.grffile : NULL);
 }
 
-uint16 GetHouseCallback(CallbackID callback, uint32 param1, uint32 param2, HouseID house_id, const Town *town, TileIndex tile, bool not_yet_constructed, uint8 initial_random_bits)
+uint16 GetHouseCallback(CallbackID callback, uint32 param1, uint32 param2, HouseID house_id, Town *town, TileIndex tile, bool not_yet_constructed, uint8 initial_random_bits)
 {
 	ResolverObject object;
 	const SpriteGroup *group;
diff --git a/src/newgrf_house.h b/src/newgrf_house.h
index 1b24a67474..62748ec82f 100644
--- a/src/newgrf_house.h
+++ b/src/newgrf_house.h
@@ -44,7 +44,7 @@ void DrawNewHouseTile(TileInfo *ti, HouseID house_id);
 void AnimateNewHouseTile(TileIndex tile);
 void AnimateNewHouseConstruction(TileIndex tile);
 
-uint16 GetHouseCallback(CallbackID callback, uint32 param1, uint32 param2, HouseID house_id, const Town *town, TileIndex tile, bool not_yet_constructed = false, uint8 initial_random_bits = 0);
+uint16 GetHouseCallback(CallbackID callback, uint32 param1, uint32 param2, HouseID house_id, Town *town, TileIndex tile, bool not_yet_constructed = false, uint8 initial_random_bits = 0);
 
 bool CanDeleteHouse(TileIndex tile);
 
diff --git a/src/newgrf_spritegroup.h b/src/newgrf_spritegroup.h
index f65a7f5c4c..c05031cca0 100644
--- a/src/newgrf_spritegroup.h
+++ b/src/newgrf_spritegroup.h
@@ -336,7 +336,7 @@ struct ResolverObject {
 		} station;
 		struct {
 			TileIndex tile;
-			const Town *town;
+			Town *town;                    ///< Town of this house
 			HouseID house_id;
 			uint16 initial_random_bits;    ///< Random bits during construction checks
 			bool not_yet_constructed;      ///< True for construction check