diff --git a/src/main/kotlin/com/android/trisolarisserver/controller/booking/BookingFlow.kt b/src/main/kotlin/com/android/trisolarisserver/controller/booking/BookingFlow.kt
index b4baa94..6b0d076 100644
--- a/src/main/kotlin/com/android/trisolarisserver/controller/booking/BookingFlow.kt
+++ b/src/main/kotlin/com/android/trisolarisserver/controller/booking/BookingFlow.kt
@@ -301,6 +301,7 @@ class BookingFlow(
     }
 
     @PostMapping("/{bookingId}/billable-nights")
+    @Transactional(readOnly = true)
     fun previewBillableNights(
         @PathVariable propertyId: UUID,
         @PathVariable bookingId: UUID,