diff --git a/lib/appenders/logstashUDP.js b/lib/appenders/logstashUDP.js
index e54e048..ee9758e 100644
--- a/lib/appenders/logstashUDP.js
+++ b/lib/appenders/logstashUDP.js
@@ -1,68 +1,72 @@
-"use strict";
-var layouts = require('../layouts')
-  , dgram = require('dgram')
-  , util = require('util');
+'use strict';
+const layouts = require('../layouts');
+const dgram = require('dgram');
+const util = require('util');
 
 function logstashUDP(config, layout) {
-  var udp = dgram.createSocket('udp4');
-  var type = config.logType ? config.logType : config.category;
+  const udp = dgram.createSocket('udp4');
+  const type = config.logType ? config.logType : config.category;
   layout = layout || layouts.dummyLayout;
+
   if (!config.fields) {
     config.fields = {};
   }
-  return function log(loggingEvent) {
 
+  return function log(loggingEvent) {
     /*
      https://gist.github.com/jordansissel/2996677
      {
-     "message"    => "hello world",
-     "@version"   => "1",
-     "@timestamp" => "2014-04-22T23:03:14.111Z",
-     "type"       => "stdin",
-     "host"       => "hello.local"
+     'message'    => 'hello world',
+     '@version'   => '1',
+     '@timestamp' => '2014-04-22T23:03:14.111Z',
+     'type'       => 'stdin',
+     'host'       => 'hello.local'
      }
      @timestamp is the ISO8601 high-precision timestamp for the event.
      @version is the version number of this json schema
      Every other field is valid and fine.
      */
-
+    /* eslint no-prototype-builtins:1,no-restricted-syntax:[1, "ForInStatement"] */
     if (loggingEvent.data.length > 1) {
-      var secondEvData = loggingEvent.data[1];
-      for (var k in secondEvData) {
-        config.fields[k] = secondEvData[k];
+      const secondEvData = loggingEvent.data[1];
+      for (const key in secondEvData) {
+        if (secondEvData.hasOwnProperty(key)) {
+          config.fields[key] = secondEvData[key];
+        }
       }
     }
     config.fields.level = loggingEvent.level.levelStr;
 
-    var logObject = {
-      "@version": "1",
-      "@timestamp": (new Date(loggingEvent.startTime)).toISOString(),
-      "type": config.logType ? config.logType : config.category,
-      "message": layout(loggingEvent),
-      "fields": config.fields
+    const logObject = {
+      '@version': '1',
+      '@timestamp': (new Date(loggingEvent.startTime)).toISOString(),
+      type: type,
+      message: layout(loggingEvent),
+      fields: config.fields
     };
     sendLog(udp, config.host, config.port, logObject);
   };
 }
 
 function sendLog(udp, host, port, logObject) {
-  var buffer = new Buffer(JSON.stringify(logObject));
-  udp.send(buffer, 0, buffer.length, port, host, function (err, bytes) {
+  const buffer = new Buffer(JSON.stringify(logObject));
+
+  /* eslint no-unused-vars:0 */
+  udp.send(buffer, 0, buffer.length, port, host, (err, bytes) => {
     if (err) {
-      console.error(
-        "log4js.logstashUDP - %s:%p Error: %s", host, port, util.inspect(err)
-      );
+      console.error('log4js.logstashUDP - %s:%p Error: %s', host, port, util.inspect(err));
     }
   });
 }
 
 function configure(config) {
-  var layout;
+  let layout;
   if (config.layout) {
     layout = layouts.layout(config.layout.type, config.layout);
   }
+
   return logstashUDP(config, layout);
 }
 
-exports.appender = logstashUDP;
-exports.configure = configure;
+module.exports.appender = logstashUDP;
+module.exports.configure = configure;