diff --git a/.travis.yml b/.travis.yml
index 87f8cd9..0de7c90 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,3 +1,3 @@
 language: node_js
 node_js:
-  - "0.10"
\ No newline at end of file
+  - 6.9
diff --git a/lib/client.js b/lib/client.js
index e6dd5ef..ba17c60 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -1,10 +1,10 @@
-var request = require('request'),
-  _ = require('lodash'),
-  _s = require('underscore.string'),
-  urlParser = require('url');
+const request = require('request');
+const _ = require('lodash');
+const _s = require('underscore.string');
+const urlParser = require('url');
 
 // Avalable APIS
-var apis = ['search', 'moreLikeThis', 'indexes', 'fields', 'documents', 'templates', 'replication'];
+const apis = ['search', 'moreLikeThis', 'indexes', 'fields', 'documents', 'templates', 'replication'];
 
 // Build API
 function buildApi(name) {
@@ -30,7 +30,7 @@ function Client(options) {
 // Make an http request to defined endpoint
 Client.prototype.request = function (options, callback) {
 
-  var url = urlParser.format(_(this.options)
+  const url = urlParser.format(_(this.options)
     .pick(['hostname', 'port', 'protocol', 'query'])
     .defaults({
       protocol: 'http',
@@ -41,12 +41,12 @@ Client.prototype.request = function (options, callback) {
 
   request(_(options)
     .defaults({
-      url: url,
+      url,
       json: true
     })
-    .value(), function (err, res, body) {
+    .value(), (err, res, body) => {
       if (err) {
-        var message = err.message;
+        let message = err.message;
 
         if (err.code === 'ECONNREFUSED') {
           message = 'Cannot connect to OpenSearchServer at ' + url;
diff --git a/lib/documents.js b/lib/documents.js
index 1169127..b186626 100644
--- a/lib/documents.js
+++ b/lib/documents.js
@@ -1,6 +1,6 @@
-var _ = require('lodash');
+const _ = require('lodash');
 
-var documents = module.exports = {
+const documents = module.exports = {
   documents: {}
 };
 
@@ -31,4 +31,4 @@ var documents = module.exports = {
     }, callback);
   };
 
-}).call(documents.documents);
\ No newline at end of file
+}).call(documents.documents);
diff --git a/lib/fields.js b/lib/fields.js
index 0864f75..4f4f9aa 100644
--- a/lib/fields.js
+++ b/lib/fields.js
@@ -1,8 +1,6 @@
-var util = require('./util');
+const util = require('./util');
 
-var fields = module.exports = {
-  fields: {}
-};
+const fields = module.exports = { fields: {} };
 
 (function () {
 
@@ -10,13 +8,13 @@ var fields = module.exports = {
   this.createOrUpdate = function (index, options, callback) {
     options = options || {};
 
-    ['indexed', 'stored', 'termVector'].forEach(function (param) {
+    ['indexed', 'stored', 'termVector'].forEach((param) => {
       if (typeof options[param] !== 'undefined')
         options[param] = util.convertParam(options[param]);
     });
 
     this.request({
-      pathname: '/services/rest/index/' + index + '/field/' + options.name,
+      pathname: `/services/rest/index/${index}/field/${options.name}`,
       method: 'PUT',
       json: options
     }, callback);
@@ -28,7 +26,7 @@ var fields = module.exports = {
   // Remove an existing field
   this.destroy = function (index, field, callback) {
     this.request({
-      pathname: '/services/rest/index/' + index + '/field/' + field,
+      pathname: `/services/rest/index/${index}/field/${field}`,
       method: 'DELETE'
     }, callback);
   };
@@ -36,7 +34,7 @@ var fields = module.exports = {
   // Set the unique and the default fields
   this.setUniqueDefault = function (index, options, callback) {
     this.request({
-      pathname: '/services/rest/index/' + index + '/field',
+      pathname: `/services/rest/index/${index}/field`,
       method: 'POST',
       qs: options
     }, callback);
@@ -45,9 +43,9 @@ var fields = module.exports = {
   // list fields
   this.list = function (index, callback) {
     this.request({
-      pathname: '/services/rest/index/' + index + '/field/',
+      pathname: `/services/rest/index/${index}/field/`,
       method: 'GET'
     }, callback);
   };
 
-}).call(fields.fields);
\ No newline at end of file
+}).call(fields.fields);
diff --git a/lib/indexes.js b/lib/indexes.js
index 9c891e2..c6af927 100644
--- a/lib/indexes.js
+++ b/lib/indexes.js
@@ -1,8 +1,6 @@
-var _ = require('lodash');
+const _ = require('lodash');
 
-var indexes = module.exports = {
-  indexes: {}
-};
+const indexes = module.exports = { indexes: {} };
 
 (function () {
 
@@ -17,8 +15,11 @@ var indexes = module.exports = {
       template: ''
     });
 
+    const { template } = options;
+    const templateQueryString = template ? '/template/' + template : '';
+
     this.request({
-      pathname: '/services/rest/index/' + index + (options.template ? '/template/' + options.template : ''),
+      pathname: `/services/rest/index/${index}${templateQueryString}`,
       method: 'POST'
     }, callback);
   };
@@ -26,7 +27,7 @@ var indexes = module.exports = {
   // Test if index exists
   this.exists = function (index, callback) {
     this.request({
-      pathname: '/services/rest/index/' + index,
+      pathname: `/services/rest/index/${index}`,
       method: 'GET'
     }, callback);
   };
@@ -34,9 +35,9 @@ var indexes = module.exports = {
   // Remove an existing index
   this.destroy = function (index, callback) {
     this.request({
-      pathname: '/services/rest/index/' + index,
+      pathname: `/services/rest/index/${index}`,
       method: 'DELETE'
     }, callback);
   };
 
-}).call(indexes.indexes);
\ No newline at end of file
+}).call(indexes.indexes);
diff --git a/lib/more-like-this.js b/lib/more-like-this.js
index 5280bd1..5acc0fa 100644
--- a/lib/more-like-this.js
+++ b/lib/more-like-this.js
@@ -1,13 +1,13 @@
-var _ = require('lodash');
+const _ = require('lodash');
 
-var moreLikeThis = module.exports = {};
+const moreLikeThis = module.exports = {};
 
 (function () {
 
   // More like this
   this.moreLikeThis = function (index, options, callback) {
     this.request({
-      pathname: '/services/rest/index/' + index + '/morelikethis',
+      pathname: `/services/rest/index/${index}/morelikethis`,
       method: 'POST',
       json: _.defaults({}, options || {}, {
         analyzerName: 'StandardAnalyzer',
@@ -25,4 +25,4 @@ var moreLikeThis = module.exports = {};
     }, callback);
   };
 
-}).call(moreLikeThis);
\ No newline at end of file
+}).call(moreLikeThis);
diff --git a/lib/oss.js b/lib/oss.js
index 858d00c..1173618 100644
--- a/lib/oss.js
+++ b/lib/oss.js
@@ -1,5 +1,5 @@
-var Client = require('./client');
-var util = require('./util');
+const Client = require('./client');
+const util = require('./util');
 
 // Create a new client
 function createClient(options) {
@@ -8,4 +8,4 @@ function createClient(options) {
 
 exports.Client = Client;
 exports.createClient = createClient;
-exports.util = util;
\ No newline at end of file
+exports.util = util;
diff --git a/lib/replication.js b/lib/replication.js
index 5df578a..4817ca6 100644
--- a/lib/replication.js
+++ b/lib/replication.js
@@ -1,12 +1,12 @@
-var _ = require('lodash');
+const _ = require('lodash');
 
-var replication = module.exports = {};
+const replication = module.exports = {};
 
 (function () {
 
   this.createReplicationIndex = function(index, searcher, callback) {
     this.request({
-      pathname: '/services/rest/index/' + index + '/replication',
+      pathname: `/services/rest/index/${index}/replication`,
       method: 'PUT',
       body: {
         replicationType: 'MAIN_INDEX',
@@ -18,16 +18,16 @@ var replication = module.exports = {};
   };
 
   this.replicate = function(index, searcher, callback) {
-    var searcherUrl = buildUrl(searcher);
+    const searcherUrl = buildUrl(searcher);
     this.request({
-      pathname: '/services/rest/index/' + index + '/replication/run',
+      pathname: `/services/rest/index/${index}/replication/run`,
       method: 'PUT',
-      search: 'name=' + searcherUrl + '/' + index
+      search: `name=${searcherUrl}/${index}`
     }, callback);
   };
 
-  function buildUrl(searcher) {
-    return searcher.protocol || 'http' + '://' + searcher.hostname + ':' + searcher.port;
+  function buildUrl({ protocol = 'http', hostname, port }) {
+    return `${protocol}://${hostname}:${port}`;
   }
 
 }).call(replication);
diff --git a/lib/search.js b/lib/search.js
index ed02297..3a611ea 100644
--- a/lib/search.js
+++ b/lib/search.js
@@ -1,6 +1,6 @@
-var _ = require('lodash');
+const _ = require('lodash');
 
-var search = module.exports = {};
+const search = module.exports = {};
 
 (function () {
 
@@ -11,10 +11,10 @@ var search = module.exports = {};
     });
 
     this.request({
-      pathname: '/services/rest/index/' + index + '/search/' + options.type,
+      pathname: `/services/rest/index/${index}/search/${options.type}`,
       method: 'POST',
       json: _.omit(options, 'type')
     }, callback);
   };
 
-}).call(search);
\ No newline at end of file
+}).call(search);
diff --git a/lib/templates.js b/lib/templates.js
index 9061bee..8227949 100644
--- a/lib/templates.js
+++ b/lib/templates.js
@@ -1,15 +1,13 @@
-var _ = require('lodash');
+const _ = require('lodash');
 
-var templates = module.exports = {
-  templates: {}
-};
+const templates = module.exports = { templates: {} };
 
 (function () {
 
   // Get a search template.
   this.get = function (index, name, callback) {
     this.request({
-      pathname: '/services/rest/index/' + index + '/search/template/' + name,
+      pathname: `/services/rest/index/${index}/search/template/${name}`,
       method: 'GET'
     }, callback);
   };
@@ -17,7 +15,7 @@ var templates = module.exports = {
   // List all search templates.
   this.list = function (index, callback) {
     this.request({
-      pathname: '/services/rest/index/' + index + '/search/template/',
+      pathname: `/services/rest/index/${index}/search/template/`,
       method: 'GET'
     }, callback);
   };
@@ -29,7 +27,7 @@ var templates = module.exports = {
     });
 
     this.request({
-      pathname: '/services/rest/index/' + index + '/search/' + options.type + '/' + name,
+      pathname: `/services/rest/index/${index}/search/${options.type}/${name}`,
       method: 'PUT',
       json: _.omit(options, 'type')
     }, callback);
@@ -41,9 +39,9 @@ var templates = module.exports = {
   // Remove an existing template.
   this.destroy = function (index, name, callback) {
     this.request({
-      pathname: '/services/rest/index/' + index + '/search/template/' + name,
+      pathname: `/services/rest/index/${index}/search/template/${name}`,
       method: 'DELETE'
     }, callback);
   };
 
-}).call(templates.templates);
\ No newline at end of file
+}).call(templates.templates);
diff --git a/lib/util.js b/lib/util.js
index b48fb64..dc62299 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -1,4 +1,4 @@
-var _ = require('lodash');
+const _ = require('lodash');
 
 function convertParam(val) {
   return val === true ? 'YES' :
@@ -7,4 +7,4 @@ function convertParam(val) {
     val;
 }
 
-exports.convertParam = convertParam;
\ No newline at end of file
+exports.convertParam = convertParam;
diff --git a/test/client.js b/test/client.js
index 76db8c6..d4bfe1d 100644
--- a/test/client.js
+++ b/test/client.js
@@ -1,31 +1,29 @@
 /* globals describe, it, beforeEach */
 
-var expect = require('chai').expect,
-  nock = require('nock'),
-  Client = require('../lib/client');
+const expect = require('chai').expect;
+const nock = require('nock');
+const Client = require('../lib/client');
 
-  nock.enableNetConnect();
+nock.enableNetConnect();
 
-describe('Client', function () {
+describe('Client', () => {
 
-  it('should have default options', function () {
-    var client = new Client();
+  it('should have default options', () => {
+    const client = new Client();
     expect(client.options).to.have.property('hostname');
     expect(client.options).to.have.property('port');
   });
 
-  describe('#request', function () {
-    describe('without credentials', function () {
-      var client;
+  describe('#request', () => {
+    describe('without credentials', () => {
+      let client;
 
-      beforeEach(function () {
+      beforeEach(() => {
         client = new Client();
 
         nock('http://localhost:9090')
           .post('/my-path')
-          .reply(200, {
-            foo: 'bar'
-          });
+          .reply(200, { foo: 'bar' });
 
         nock('http://localhost:9090')
           .post('/my-error-path')
@@ -37,28 +35,19 @@ describe('Client', function () {
 
       });
 
-      it('should be possible to make a request', function (done) {
+      it('should be possible to make a request', done => {
 
-        client.request({
-          pathname: '/my-path',
-          method: 'POST'
-        }, function (err, res) {
+        client.request({ pathname: '/my-path', method: 'POST' }, (err, res) => {
           if (err) return done(err);
 
-          expect(res).to.deep.equal({
-            foo: 'bar'
-          });
-
+          expect(res).to.deep.equal({ foo: 'bar' });
           done();
         });
       });
 
-      it('should handle error correctly', function (done) {
+      it('should handle error correctly', done => {
 
-        client.request({
-          pathname: '/my-error-path',
-          method: 'POST'
-        }, function (err, res) {
+        client.request({ pathname: '/my-error-path', method: 'POST' }, (err, res) => {
           expect(err instanceof Error).to.be.true;
           expect(err.message).to.be.equal('My error');
           expect(res).to.be.undefined;
@@ -67,12 +56,9 @@ describe('Client', function () {
         });
       });
 
-      it('should handle OSS internal error correctly', function (done) {
+      it('should handle OSS internal error correctly', done => {
 
-        client.request({
-          pathname: '/my-internal-error-path',
-          method: 'POST'
-        }, function (err, res) {
+        client.request({ pathname: '/my-internal-error-path', method: 'POST' }, (err, res) => {
           expect(err instanceof Error).to.be.true;
           expect(err.message).to.be.equal('');
           expect(res).to.be.undefined;
@@ -81,21 +67,15 @@ describe('Client', function () {
         });
       });
 
-      describe('when the server is not reachable', function() {
+      describe('when the server is not reachable', () => {
 
-        beforeEach(function() {
-          client = new Client({
-            hostname: 'localhost',
-            port: 99999999
-          });
+        beforeEach(() => {
+          client = new Client({ hostname: 'localhost', port: 8080 });
         });
 
-        it('gives a usefull error message', function(done) {
-          client.request({
-            pathname: '/my-path',
-            method: 'POST'
-          }, function(err) {
-            var msg = 'Cannot connect to OpenSearchServer at http://localhost:99999999/my-path';
+        it('gives a usefull error message', done => {
+          client.request({ pathname: '/my-path', method: 'POST' }, err => {
+            const msg = 'Cannot connect to OpenSearchServer at http://localhost:8080/my-path';
             expect(err.message).to.equals(msg);
             done();
           });
@@ -103,79 +83,50 @@ describe('Client', function () {
       });
     });
 
-    describe('with credentials', function () {
-      var client;
+    describe('with credentials', () => {
+      let client;
 
-      beforeEach(function () {
-        client = new Client({
-          login: 'mylogin',
-          key: 'mykey'
-        });
+      beforeEach(() => {
+        client = new Client({ login: 'mylogin', key: 'mykey' });
 
         nock('http://localhost:9090')
           .post('/my-path?login=mylogin&key=mykey')
-          .reply(200, {
-            foo: 'bar'
-          });
+          .reply(200, { foo: 'bar' });
       });
 
-      it('should be possible to make a request', function (done) {
-        client.request({
-          pathname: '/my-path',
-          method: 'POST'
-        }, function (err, res) {
+      it('should be possible to make a request', done => {
+        client.request({ pathname: '/my-path', method: 'POST' }, (err, res) => {
           if (err) return done(err);
-
-          expect(res).to.deep.equal({
-            foo: 'bar'
-          });
-
+          expect(res).to.deep.equal({ foo: 'bar' });
           done();
         });
       });
     });
   });
 
-  describe('instances', function () {
+  describe('instances', () => {
 
-    beforeEach(function () {
+    beforeEach(() => {
       nock('http://host1:9090')
         .get('/x')
-        .reply(200, {
-          host: 1
-        });
+        .reply(200, { host: 1 });
 
       nock('http://host2:9090')
         .get('/x')
-        .reply(200, {
-          host: 2
-        });
+        .reply(200, { host: 2 });
     });
 
-    it('must be independent', function () {
-      var client1 = new Client({
-        hostname: 'host1'
-      });
-
-      var client2 = new Client({
-        hostname: 'host2'
-      });
+    it('must be independent', () => {
+      const client1 = new Client({ hostname: 'host1' });
+      const client2 = new Client({ hostname: 'host2' });
 
-      client1.indexes.request({
-        pathname: 'x'
-      }, function (err, res) {
-        expect(res).to.deep.equal({
-          host: 1
-        });
+      client1.indexes.request({ pathname: 'x' }, (err, res) => {
+        expect(res).to.deep.equal({ host: 1 });
       });
 
-      client2.indexes.request({
-        pathname: 'x'
-      }, function (err, res) {
-        expect(res).to.deep.equal({
-          host: 2
-        });
+      client2.indexes.request({ pathname: 'x' }, function (err, res) {
+        expect(res).to.deep.equal({ host: 2 });
       });
     });
   });
-});
\ No newline at end of file
+});
diff --git a/test/documents.js b/test/documents.js
index 87448b5..d22857f 100644
--- a/test/documents.js
+++ b/test/documents.js
@@ -1,27 +1,27 @@
 /* globals describe, it, beforeEach */
 
-var chai = require('chai').use(require('sinon-chai')),
-  expect = chai.expect,
-  sinon = require('sinon'),
-  oss = require('../');
+const chai = require('chai').use(require('sinon-chai'));
+const expect = chai.expect;
+const sinon = require('sinon');
+const oss = require('../');
 
-describe('Documents', function () {
+describe('Documents', () => {
 
-  var client, rq;
+  let client, rq;
 
-  beforeEach(function () {
+  beforeEach(() => {
     client = oss.createClient();
     rq = sinon.stub(client.documents, 'request');
   });
 
-  describe('#createOrUpdate', function () {
+  describe('#createOrUpdate', () => {
 
-    it('should be possible to create a single document', function () {
+    it('should be possible to create a single document', () => {
 
       client.documents.createOrUpdate('my_index', {
         fields: [
-          {name: 'id', value: 1},
-          {name: 'text', value: 'my value'}
+          { name: 'id', value: 1 },
+          { name: 'text', value: 'my value' }
         ]
       });
 
@@ -31,27 +31,27 @@ describe('Documents', function () {
         json: [
           {
             fields: [
-              {name: 'id', value: 1},
-              {name: 'text', value: 'my value'}
+              { name: 'id', value: 1 },
+              { name: 'text', value: 'my value' }
             ]
           }
         ]
       });
     });
 
-    it('should be possible to create multiple documents', function () {
+    it('should be possible to create multiple documents', () => {
 
       client.documents.createOrUpdate('my_index', [
         {
           fields: [
-            {name: 'id', value: 1},
-            {name: 'text', value: 'my value'}
+            { name: 'id', value: 1 },
+            { name: 'text', value: 'my value' }
           ]
         },
         {
           fields: [
-            {name: 'id', value: 2},
-            {name: 'text', value: 'my second value'}
+            { name: 'id', value: 2 },
+            { name: 'text', value: 'my second value' }
           ]
         }
       ]);
@@ -62,26 +62,26 @@ describe('Documents', function () {
         json: [
           {
             fields: [
-              {name: 'id', value: 1},
-              {name: 'text', value: 'my value'}
+              { name: 'id', value: 1 },
+              { name: 'text', value: 'my value' }
             ]
           },
           {
             fields: [
-              {name: 'id', value: 2},
-              {name: 'text', value: 'my second value'}
+              { name: 'id', value: 2 },
+              { name: 'text', value: 'my second value' }
             ]
           }
         ]
       });
     });
 
-    it('should be possible to update a single document', function () {
+    it('should be possible to update a single document', () => {
 
       client.documents.createOrUpdate('my_index', {
         fields: [
-          {name: 'id', value: 1},
-          {name: 'text', value: 'my new value'}
+          { name: 'id', value: 1 },
+          { name: 'text', value: 'my new value' }
         ]
       });
 
@@ -91,8 +91,8 @@ describe('Documents', function () {
         json: [
           {
             fields: [
-              {name: 'id', value: 1},
-              {name: 'text', value: 'my new value'}
+              { name: 'id', value: 1 },
+              { name: 'text', value: 'my new value' }
             ]
           }
         ]
@@ -100,14 +100,11 @@ describe('Documents', function () {
     });
   });
 
-  describe('#destroy', function () {
+  describe('#destroy', () => {
 
-    it('should be possible to destroy an index', function () {
+    it('should be possible to destroy an index', () => {
 
-      client.documents.destroy('my_index', {
-        field: 'id',
-        values: 1
-      });
+      client.documents.destroy('my_index', { field: 'id', values: 1 });
 
       expect(rq).to.be.calledWith({
         method: 'DELETE',
@@ -116,4 +113,4 @@ describe('Documents', function () {
       });
     });
   });
-});
\ No newline at end of file
+});
diff --git a/test/fields.js b/test/fields.js
index 7ba1c08..62ba8a2 100644
--- a/test/fields.js
+++ b/test/fields.js
@@ -1,59 +1,47 @@
 /* globals describe, it, beforeEach */
 
-var chai = require('chai').use(require('sinon-chai')),
-  expect = chai.expect,
-  sinon = require('sinon'),
-  oss = require('../');
+const chai = require('chai').use(require('sinon-chai'));
+const expect = chai.expect;
+const sinon = require('sinon');
+const oss = require('../');
 
-describe('Fields', function () {
+describe('Fields', () => {
 
-  var client, rq;
+  let client, rq;
 
-  beforeEach(function () {
+  beforeEach(() => {
     client = oss.createClient();
     rq = sinon.stub(client.fields, 'request');
   });
 
-  describe('#createOrUpdate', function () {
+  describe('#createOrUpdate', () => {
 
-    it('should be possible to create a field', function () {
+    it('should be possible to create a field', () => {
 
-      client.fields.createOrUpdate('my_index', {
-        name: 'my_field',
-        stored: true
-      });
+      client.fields.createOrUpdate('my_index', { name: 'my_field', stored: true });
 
       expect(rq).to.be.calledWith({
         method: 'PUT',
         pathname: '/services/rest/index/my_index/field/my_field',
-        json: {
-          name: 'my_field',
-          stored: 'YES'
-        }
+        json: { name: 'my_field', stored: 'YES' }
       });
     });
 
-    it('should be possible to update a field', function () {
+    it('should be possible to update a field', () => {
 
-      client.fields.createOrUpdate('my_index', {
-        name: 'my_field',
-        stored: true
-      });
+      client.fields.createOrUpdate('my_index', { name: 'my_field', stored: true });
 
       expect(rq).to.be.calledWith({
         method: 'PUT',
         pathname: '/services/rest/index/my_index/field/my_field',
-        json: {
-          name: 'my_field',
-          stored: 'YES'
-        }
+        json: { name: 'my_field', stored: 'YES' }
       });
     });
   });
 
-  describe('#destroy', function () {
+  describe('#destroy', () => {
 
-    it('should be possible to destroy an index', function () {
+    it('should be possible to destroy an index', () => {
 
       client.fields.destroy('my_index', 'my_field');
 
@@ -64,29 +52,23 @@ describe('Fields', function () {
     });
   });
 
-  describe('#setUniqueDefault', function () {
+  describe('#setUniqueDefault', () => {
 
-    it('should be possible to define unique and default field', function () {
+    it('should be possible to define unique and default field', () => {
 
-      client.fields.setUniqueDefault('my_index', {
-        default: 'my_default_field',
-        unique: 'my_unique_field'
-      });
+      client.fields.setUniqueDefault('my_index', { default: 'my_default_field', unique: 'my_unique_field' });
 
       expect(rq).to.be.calledWith({
         method: 'POST',
         pathname: '/services/rest/index/my_index/field',
-        qs: {
-          default: 'my_default_field',
-          unique: 'my_unique_field'
-        }
+        qs: { default: 'my_default_field', unique: 'my_unique_field' }
       });
     });
   });
 
-  describe('#list', function () {
+  describe('#list', () => {
 
-    it('should be possible to list the fileds of an index', function () {
+    it('should be possible to list the fileds of an index', () => {
 
       client.fields.list('my_index');
 
@@ -96,4 +78,4 @@ describe('Fields', function () {
       });
     });
   });
-});
\ No newline at end of file
+});
diff --git a/test/indexes.js b/test/indexes.js
index 423606b..b29d0b0 100644
--- a/test/indexes.js
+++ b/test/indexes.js
@@ -1,22 +1,22 @@
 /* globals describe, it, beforeEach */
 
-var chai = require('chai').use(require('sinon-chai')),
-  expect = chai.expect,
-  sinon = require('sinon'),
-  oss = require('../');
+const chai = require('chai').use(require('sinon-chai'));
+const expect = chai.expect;
+const sinon = require('sinon');
+const oss = require('../');
 
-describe('Indexes', function () {
+describe('Indexes', () => {
 
-  var client, rq;
+  let client, rq;
 
-  beforeEach(function () {
+  beforeEach(() => {
     client = oss.createClient();
     rq = sinon.stub(client.indexes, 'request');
   });
 
-  describe('#create', function () {
+  describe('#create', () => {
 
-    it('should be possible to create an index', function () {
+    it('should be possible to create an index', () => {
 
       client.indexes.create('my_index');
 
@@ -26,11 +26,9 @@ describe('Indexes', function () {
       });
     });
 
-    it('should be possible to create an index with a template', function () {
+    it('should be possible to create an index with a template', () => {
 
-      client.indexes.create('my_index', {
-        template: 'my_template'
-      });
+      client.indexes.create('my_index', { template: 'my_template' });
 
       expect(rq).to.be.calledWith({
         method: 'POST',
@@ -39,9 +37,9 @@ describe('Indexes', function () {
     });
   });
 
-  describe('#exists', function () {
+  describe('#exists', () => {
 
-    it('should return if an index exists', function () {
+    it('should return if an index exists', () => {
 
       client.indexes.exists('my_index');
 
@@ -52,9 +50,9 @@ describe('Indexes', function () {
     });
   });
 
-  describe('#destroy', function () {
+  describe('#destroy', () => {
 
-    it('should be possible to destroy an index', function () {
+    it('should be possible to destroy an index', () => {
 
       client.indexes.destroy('my_index');
 
@@ -64,4 +62,4 @@ describe('Indexes', function () {
       });
     });
   });
-});
\ No newline at end of file
+});
diff --git a/test/more-like-this.js b/test/more-like-this.js
index 7c4bb54..c3a8cba 100644
--- a/test/more-like-this.js
+++ b/test/more-like-this.js
@@ -1,26 +1,22 @@
-'use strict';
-
 /* globals describe, it, beforeEach */
 
-var oss = require('../');
-var chai = require('chai').use(require('sinon-chai'));
-var sinon = require('sinon');
-var expect = chai.expect;
+const oss = require('../');
+const chai = require('chai').use(require('sinon-chai'));
+const sinon = require('sinon');
+const expect = chai.expect;
 
-describe('More like this', function () {
+describe('More like this', () => {
 
-  var client, rq;
+  let client, rq;
 
-  beforeEach(function () {
+  beforeEach(() => {
     client = oss.createClient();
     rq = sinon.stub(client, 'request');
   });
 
-  it('should be possible to request more like this', function () {
+  it('should be possible to request more like this', () => {
 
-    client.moreLikeThis('my_index', {
-      minWordLen: 2
-    });
+    client.moreLikeThis('my_index', { minWordLen: 2 });
 
     expect(rq).to.be.calledWith({
       json: {
@@ -40,4 +36,4 @@ describe('More like this', function () {
       pathname: '/services/rest/index/my_index/morelikethis'
     });
   });
-});
\ No newline at end of file
+});
diff --git a/test/replication.js b/test/replication.js
index 12905df..45ce2c9 100644
--- a/test/replication.js
+++ b/test/replication.js
@@ -1,26 +1,23 @@
 /* globals describe, it, beforeEach */
 
-var chai = require('chai').use(require('sinon-chai')),
-  expect = chai.expect,
-  sinon = require('sinon'),
-  oss = require('../');
+const chai = require('chai').use(require('sinon-chai'));
+const expect = chai.expect;
+const sinon = require('sinon');
+const oss = require('../');
 
-describe('Replication', function () {
+describe('Replication', () => {
 
-  var client, request, searcher;
+  let client, request, searcher;
 
-  beforeEach(function () {
+  beforeEach(() => {
     client = oss.createClient();
     request = sinon.stub(client, 'request');
-    searcher = {
-      hostname: 'searcher-oss.com',
-      port: 8000
-    };
+    searcher = { hostname: 'searcher-oss.com', port: 8000 };
   });
 
-  describe('#createReplicationIndex', function () {
+  describe('#createReplicationIndex', () => {
 
-    it('should request the API to create a replication index', function () {
+    it('should request the API to create a replication index', () => {
 
       client.createReplicationIndex('my_index', searcher);
 
@@ -36,7 +33,7 @@ describe('Replication', function () {
       });
     });
 
-    it('should request the API to start a replication on an index', function () {
+    it('should request the API to start a replication on an index', () => {
       client.replicate('my_index', searcher);
 
       expect(request).to.be.calledWithMatch({
diff --git a/test/search.js b/test/search.js
index ecf5096..4d7c8ac 100644
--- a/test/search.js
+++ b/test/search.js
@@ -1,31 +1,27 @@
 /* globals describe, it, beforeEach */
 
-var chai = require('chai').use(require('sinon-chai')),
-  expect = chai.expect,
-  sinon = require('sinon'),
-  oss = require('../');
+const chai = require('chai').use(require('sinon-chai'));
+const expect = chai.expect;
+const sinon = require('sinon');
+const oss = require('../');
 
-describe('Search', function () {
+describe('Search', () => {
 
-  var client, rq;
+  let client, rq;
 
   beforeEach(function () {
     client = oss.createClient();
     rq = sinon.stub(client, 'request');
   });
 
-  it('should be possible to make a search', function () {
+  it('should be possible to make a search', () => {
 
-    client.search('my_index', {
-      query: 'My query'
-    });
+    client.search('my_index', { query: 'My query' });
 
     expect(rq).to.be.calledWith({
-      json: {
-        query: 'My query'
-      },
+      json: { query: 'My query' },
       method: 'POST',
       pathname: '/services/rest/index/my_index/search/field'
     });
   });
-});
\ No newline at end of file
+});
diff --git a/test/templates.js b/test/templates.js
index 29c0e1f..da53f55 100644
--- a/test/templates.js
+++ b/test/templates.js
@@ -1,21 +1,21 @@
 /* globals describe, it, beforeEach */
 
-var chai = require('chai').use(require('sinon-chai')),
-  expect = chai.expect,
-  sinon = require('sinon'),
-  oss = require('../');
+const chai = require('chai').use(require('sinon-chai'));
+const expect = chai.expect;
+const sinon = require('sinon');
+const oss = require('../');
 
-describe('Templates', function () {
+describe('Templates', () => {
 
-  var client, rq;
+  let client, rq;
 
-  beforeEach(function () {
+  beforeEach(() => {
     client = oss.createClient();
     rq = sinon.stub(client.templates, 'request');
   });
 
-  describe('#createOrUpdate', function () {
-    it('should be possible to create a field', function () {
+  describe('#createOrUpdate', () => {
+    it('should be possible to create a field', () => {
 
       client.templates.createOrUpdate('my_index', 'my_template', {
         returnedFields: ['my_field']
@@ -24,15 +24,13 @@ describe('Templates', function () {
       expect(rq).to.be.calledWith({
         method: 'PUT',
         pathname: '/services/rest/index/my_index/search/field/my_template',
-        json: {
-          returnedFields: ['my_field']
-        }
+        json: { returnedFields: ['my_field'] }
       });
     });
   });
 
-  describe('#destroy', function () {
-    it('should be possible to destroy an index', function () {
+  describe('#destroy', () => {
+    it('should be possible to destroy an index', () => {
 
       client.templates.destroy('my_index', 'my_template');
 
@@ -43,8 +41,8 @@ describe('Templates', function () {
     });
   });
 
-  describe('#list', function () {
-    it('should be possible to list templates', function () {
+  describe('#list', () => {
+    it('should be possible to list templates', () => {
 
       client.templates.list('my_index');
 
@@ -55,8 +53,8 @@ describe('Templates', function () {
     });
   });
 
-  describe('#get', function () {
-    it('should be possible to get a template', function () {
+  describe('#get', () => {
+    it('should be possible to get a template', () => {
 
       client.templates.get('my_index', 'my_template');
 
@@ -66,4 +64,4 @@ describe('Templates', function () {
       });
     });
   });
-});
\ No newline at end of file
+});
diff --git a/test/util.js b/test/util.js
index 18e10f2..7cfd443 100644
--- a/test/util.js
+++ b/test/util.js
@@ -1,24 +1,24 @@
 /* globals describe, it */
 
-var expect = require('chai').expect,
-  util = require('../lib/util');
+const expect = require('chai').expect;
+const util = require('../lib/util');
 
-describe('Util', function () {
+describe('Util', () => {
 
-  describe('#convertParam', function () {
+  describe('#convertParam', () => {
 
-    it('should transform true and false to "YES" and "NO"', function () {
+    it('should transform true and false to "YES" and "NO"', () => {
       expect(util.convertParam(true)).to.equal('YES');
       expect(util.convertParam(false)).to.equal('NO');
     });
 
-    it('should uppercase string', function () {
+    it('should uppercase string', () => {
       expect(util.convertParam('my_string')).to.equal('MY_STRING');
     });
 
-    it('should do nothing on other parameters', function () {
-      var object = {kung: 'foo'};
+    it('should do nothing on other parameters', () => {
+      const object = { kung: 'foo' };
       expect(util.convertParam(object)).to.equal(object);
     });
   });
-});
\ No newline at end of file
+});