diff --git a/src/newgrf_spritegroup.h b/src/newgrf_spritegroup.h
--- a/src/newgrf_spritegroup.h
+++ b/src/newgrf_spritegroup.h
@@ -341,6 +341,7 @@ struct ResolverObject {
 			HouseID house_id;
 			uint16 initial_random_bits;    ///< Random bits during construction checks
 			bool not_yet_constructed;      ///< True for construction check
+			uint32 watched_cargo_triggers; ///< Cargo types that triggered the watched cargo callback.
 		} house;
 		struct {
 			TileIndex tile;