diff --git a/back/models/vn-user.js b/back/models/vn-user.js
index 29c51509dc..02ad3e79b9 100644
--- a/back/models/vn-user.js
+++ b/back/models/vn-user.js
@@ -124,6 +124,14 @@ module.exports = function(Self) {
 
         return email.send();
     });
+
+    /**
+     * Sign-in validate.     *
+     * @param {Integer} user The user
+     * @param {Object} userToken Options
+     * @param {Object} token accessToken
+     * @param {Object} ctx context
+     */
     Self.signInValidate = async(user, userToken, token, ctx) => {
         const [[key, value]] = Object.entries(Self.userUses(user));
         const isOwner = Self.rawSql(`SELECT ? = ? `, [userToken[key], value]);