diff --git a/libs/Db.js b/libs/Db.js
index f97ebbf..e117cab 100644
--- a/libs/Db.js
+++ b/libs/Db.js
@@ -16,7 +16,7 @@ class Db {
         createdAt: 'desc'
       })
       .limit(1)
-      .exec(function (err, last) {
+      .exec((err, last) => {
         if (err ||
         last.length === 0 ||
         (last[0] !== undefined &&