diff --git a/src/fare-contract/types.ts b/src/fare-contract/types.ts
index 51f8b61..5379d18 100644
--- a/src/fare-contract/types.ts
+++ b/src/fare-contract/types.ts
@@ -38,24 +38,24 @@ export type UsedAccessType = z.infer<typeof UsedAccessType>;
  */
 export const TravelRightType = z.object({
   id: z.string(),
-  customerAccountId: z.string().optional(),
+  customerAccountId: z.string().nullish(),
   status: z.nativeEnum(TravelRightStatus),
   fareProductRef: z.string(),
   startDateTime: z.date(),
   endDateTime: z.date(),
-  usageValidityPeriodRef: z.string().optional(),
-  userProfileRef: z.string().optional(),
+  usageValidityPeriodRef: z.string().nullish(),
+  userProfileRef: z.string().nullish(),
   authorityRef: z.string(),
-  tariffZoneRefs: z.array(z.string()).optional(),
-  fareZoneRefs: z.array(z.string()).optional(),
-  startPointRef: z.string().optional(),
-  endPointRef: z.string().optional(),
-  direction: z.nativeEnum(TravelRightDirection).optional(),
-  maximumNumberOfAccesses: z.number().optional(),
-  numberOfUsedAccesses: z.number().optional(),
-  usedAccesses: z.array(UsedAccessType).optional(),
-  schoolName: z.string().optional(),
-  travelerName: z.string().optional(),
+  tariffZoneRefs: z.array(z.string()).nullish(),
+  fareZoneRefs: z.array(z.string()).nullish(),
+  startPointRef: z.string().nullish(),
+  endPointRef: z.string().nullish(),
+  direction: z.nativeEnum(TravelRightDirection).nullish(),
+  maximumNumberOfAccesses: z.number().nullish(),
+  numberOfUsedAccesses: z.number().nullish(),
+  usedAccesses: z.array(UsedAccessType).nullish(),
+  schoolName: z.string().nullish(),
+  travelerName: z.string().nullish(),
 });
 export type TravelRightType = z.infer<typeof TravelRightType>;
 
@@ -78,14 +78,14 @@ export const FareContractType = z.object({
   id: z.string(),
   customerAccountId: z.string(),
   orderId: z.string(),
-  bookingId: z.string().uuid().optional(),
+  bookingId: z.string().uuid().nullish(),
   paymentType: z.array(z.string()),
-  qrCode: z.string().optional(),
+  qrCode: z.string().nullish(),
   state: z.nativeEnum(FareContractState),
   totalAmount: z.string(),
   totalTaxAmount: z.string(),
   travelRights: z.array(TravelRightType).nonempty(),
   version: z.string(),
-  purchasedBy: z.string().optional(),
+  purchasedBy: z.string().nullish(),
 });
 export type FareContractType = z.infer<typeof FareContractType>;