diff --git a/src/things/abstract/thing-that-can-be-offered.ts b/src/things/abstract/thing-that-can-be-offered.ts
index a7c6873b..5d14650e 100644
--- a/src/things/abstract/thing-that-can-be-offered.ts
+++ b/src/things/abstract/thing-that-can-be-offered.ts
@@ -107,7 +107,7 @@ export interface SCThingThatCanBeOfferedOffer<T extends SCPriceGroup>
   /**
    * List of prices that are distinct for specific groups
    */
-  prices: T;
+  prices?: T;
 
   /**
    * Provider of an offer