diff --git a/geneit_app/src/dialogs/accommodations/UpdateReservationDialog.tsx b/geneit_app/src/dialogs/accommodations/UpdateReservationDialog.tsx
index 841aae9..7a480e9 100644
--- a/geneit_app/src/dialogs/accommodations/UpdateReservationDialog.tsx
+++ b/geneit_app/src/dialogs/accommodations/UpdateReservationDialog.tsx
@@ -101,9 +101,11 @@ export function UpdateReservationDialog(p: {
         <Button
           onClick={submit}
           disabled={
-            (reservation?.accommodation_id ?? -1) > 0 &&
-            (reservation?.start ?? -1) > 0 &&
-            (reservation?.end ?? -1) > (reservation?.start ?? 0)
+            !(
+              (reservation?.accommodation_id ?? -1) > 0 &&
+              (reservation?.start ?? -1) > 0 &&
+              (reservation?.end ?? -1) > (reservation?.start ?? 0)
+            )
           }
         >
           {p.create ? "Créer" : "Mettre à jour"}