diff --git a/src/kernel/types.h b/src/kernel/types.h
index 23cef5f51..820f4b698 100644
--- a/src/kernel/types.h
+++ b/src/kernel/types.h
@@ -39,6 +39,7 @@ struct building;
 struct building_type;
 struct curse;
 struct curse_type;
+struct castorder;
 struct equipment;
 struct faction;
 struct fighter;