diff --git a/apps/scandic-web/server/routers/booking/input.ts b/apps/scandic-web/server/routers/booking/input.ts
index 33c034938..602d592ae 100644
--- a/apps/scandic-web/server/routers/booking/input.ts
+++ b/apps/scandic-web/server/routers/booking/input.ts
@@ -7,7 +7,7 @@ const roomsSchema = z
   .array(
     z.object({
       adults: z.number().int().nonnegative(),
-      bookingCode: z.string().optional(),
+      bookingCode: z.string().nullish(),
       childrenAges: z
         .array(
           z.object({