diff --git a/back/methods/postcode/filter.js b/back/methods/postcode/filter.js
index 53f25b7d4..0c97c61c5 100644
--- a/back/methods/postcode/filter.js
+++ b/back/methods/postcode/filter.js
@@ -15,8 +15,8 @@ module.exports = Self => {
     });
     Self.filter = async(ctx, filter, options) => {
         const {Postcode} = Self.app.models;
-        let {value} = ctx.where;
-        let limit = ctx.where?.limit ?? 30;
+        const {value} = ctx.where;
+        const limit = ctx.where?.limit ?? 30;
         return await Postcode.rawSql(`
         SELECT pc.code, t.name as town, p.name as province , c.country
         FROM postCode pc