diff --git a/.eslintrc-base.json b/.eslintrc-base.json
index bdc20ed..abc4514 100644
--- a/.eslintrc-base.json
+++ b/.eslintrc-base.json
@@ -5,6 +5,9 @@
   "env": {
     "es6": true
   },
+  "parserOptions": {
+    "ecmaVersion": 2019
+  },
   "rules": {
     "indent": [
       "error",
diff --git a/lib/request.js b/lib/request.js
index 7905ece..1cd8472 100644
--- a/lib/request.js
+++ b/lib/request.js
@@ -33,17 +33,15 @@ const send = options => new Promise((resolve, reject) => {
     });
 });
 
-const sendAndRetry = options => send(options).then(
-    response => {
-        if (response.statusCode === 401) {
-            return refreshToken().then(token => {
-                _token = token;
-                return send(options);
-            });
-        }
-        return response;
+const sendAndRetry = async options => {
+    const response = await send(options);
+    if (response.statusCode === 401) {
+        const token = await refreshToken();
+        _token = token;
+        return send(options);
     }
-);
+    return response.body;
+};
 
 /**
  * Send a GET request to the authorization authority.
diff --git a/lib/services/rol.js b/lib/services/rol.js
index fd7cc1b..b6153af 100644
--- a/lib/services/rol.js
+++ b/lib/services/rol.js
@@ -7,11 +7,8 @@ module.exports = class RolService {
      * Fetch all the roles.
      * @returns {Promise<Array<Rol>>} A promise with the array of roles.
      */
-    static fetch() {
-        return request.get(ENDPOINT).then(
-            response => response.body.roles.map(
-                rol => new Rol(rol)
-            )
-        );
+    static async fetch() {
+        const {roles} = await request.get(ENDPOINT);
+        return roles.map(rol => new Rol(rol));
     }
 };
diff --git a/lib/services/user.js b/lib/services/user.js
index 2137cfa..f525acf 100644
--- a/lib/services/user.js
+++ b/lib/services/user.js
@@ -7,12 +7,9 @@ module.exports = class UserService {
      * Fetch all the users.
      * @returns {Promise<Array<User>>} A promise with the array of users.
      */
-    static fetchAll() {
-        return request.get(`${ENDPOINT}all`).then(
-            response => response.body.users.map(
-                user => new User(user)
-            )
-        );
+    static async fetchAll() {
+        const {users} = await request.get(`${ENDPOINT}all`);
+        return users.map(user => new User(user));
     }
 
     /**
@@ -20,10 +17,9 @@ module.exports = class UserService {
      * @param id
      * @returns {Promise<User>} A promise with the found user.an
      */
-    static fetchOne(id) {
-        return request.get(`${ENDPOINT}${id}`).then(
-            response => new User(response.body.user)
-        );
+    static async fetchOne(id) {
+        const {user} = await request.get(`${ENDPOINT}${id}`);
+        return new User(user);
     }
 
     /**
@@ -31,13 +27,10 @@ module.exports = class UserService {
      * @param {Array<String>} ids
      * @returns {Promise<Array<User>>}
      */
-    static fetch(ids) {
+    static async fetch(ids) {
         const idsString = ids && ids.length ? ids.join(',') : undefined;
-        return request.get(ENDPOINT, {ids: idsString}).then(
-            response => response.body.users.map(
-                user => new User(user)
-            )
-        );
+        const {users} = await request.get(ENDPOINT, {ids: idsString});
+        return users.map(user => new User(user));
     }
 
     // static fetch(rol = undefined, ids = undefined, term = undefined) {
@@ -49,12 +42,9 @@ module.exports = class UserService {
      * @param {String} opts.term Terms to filter.
      * @returns {Promise<Array<User>>}
      */
-    static search({rol, state, term}) {
-        return request.get(ENDPOINT, {rol, state, term}).then(
-            response => response.body.users.map(
-                user => new User(user)
-            )
-        );
+    static async search({rol, state, term}) {
+        const {users} = await request.get(ENDPOINT, {rol, state, term});
+        return users.map(user => new User(user));
     }
 
     /**
@@ -63,10 +53,9 @@ module.exports = class UserService {
      * @param {Array<String>} roles
      * @returns {Promise<User>}
      */
-    static add(id, roles) {
-        return request.put(`${ENDPOINT}${id}`, {roles}).then(
-            response => new User(response.body.user)
-        );
+    static async add(id, roles) {
+        const {user} = await request.put(`${ENDPOINT}${id}`, {roles});
+        return new User(user);
     }
 
     /**