diff --git a/lib/ip.js b/lib/ip.js
index 0e52fc5..f3480a6 100644
--- a/lib/ip.js
+++ b/lib/ip.js
@@ -1,11 +1,11 @@
-const ip = exports;
-const { Buffer } = require('buffer');
-const os = require('os');
+var ip = exports;
+var { Buffer } = require('buffer');
+var os = require('os');
 
 ip.toBuffer = function (ip, buff, offset) {
   offset = ~~offset;
 
-  let result;
+  var result;
 
   if (this.isV4Format(ip)) {
     result = buff || new Buffer(offset + 4);
@@ -13,12 +13,12 @@ ip.toBuffer = function (ip, buff, offset) {
       result[offset++] = parseInt(byte, 10) & 0xff;
     });
   } else if (this.isV6Format(ip)) {
-    const sections = ip.split(':', 8);
+    var sections = ip.split(':', 8);
 
-    let i;
+    var i;
     for (i = 0; i < sections.length; i++) {
-      const isv4 = this.isV4Format(sections[i]);
-      let v4Buffer;
+      var isv4 = this.isV4Format(sections[i]);
+      var v4Buffer;
 
       if (isv4) {
         v4Buffer = this.toBuffer(sections[i]);
@@ -36,16 +36,16 @@ ip.toBuffer = function (ip, buff, offset) {
       while (sections.length < 8) sections.push('0');
     } else if (sections.length < 8) {
       for (i = 0; i < sections.length && sections[i] !== ''; i++);
-      const argv = [i, 1];
+      var argv = [i, 1];
       for (i = 9 - sections.length; i > 0; i--) {
         argv.push('0');
       }
-      sections.splice(...argv);
+      sections.splice.apply(sections, argv);
     }
 
     result = buff || new Buffer(offset + 16);
     for (i = 0; i < sections.length; i++) {
-      const word = parseInt(sections[i], 16);
+      var word = parseInt(sections[i], 16);
       result[offset++] = (word >> 8) & 0xff;
       result[offset++] = word & 0xff;
     }
@@ -62,16 +62,17 @@ ip.toString = function (buff, offset, length) {
   offset = ~~offset;
   length = length || (buff.length - offset);
 
-  let result = [];
+  var result = [];
+  var i;
   if (length === 4) {
     // IPv4
-    for (let i = 0; i < length; i++) {
+    for (i = 0; i < length; i++) {
       result.push(buff[offset + i]);
     }
     result = result.join('.');
   } else if (length === 16) {
     // IPv6
-    for (let i = 0; i < length; i += 2) {
+    for (i = 0; i < length; i += 2) {
       result.push(buff.readUInt16BE(offset + i).toString(16));
     }
     result = result.join(':');
@@ -82,8 +83,8 @@ ip.toString = function (buff, offset, length) {
   return result;
 };
 
-const ipv4Regex = /^(\d{1,3}\.){3,3}\d{1,3}$/;
-const ipv6Regex = /^(::)?(((\d{1,3}\.){3}(\d{1,3}){1})?([0-9a-f]){0,4}:{0,2}){1,8}(::)?$/i;
+var ipv4Regex = /^(\d{1,3}\.){3,3}\d{1,3}$/;
+var ipv6Regex = /^(::)?(((\d{1,3}\.){3}(\d{1,3}){1})?([0-9a-f]){0,4}:{0,2}){1,8}(::)?$/i;
 
 ip.isV4Format = function (ip) {
   return ipv4Regex.test(ip);
@@ -110,14 +111,14 @@ ip.fromPrefixLen = function (prefixlen, family) {
     family = _normalizeFamily(family);
   }
 
-  let len = 4;
+  var len = 4;
   if (family === 'ipv6') {
     len = 16;
   }
-  const buff = new Buffer(len);
+  var buff = new Buffer(len);
 
-  for (let i = 0, n = buff.length; i < n; ++i) {
-    let bits = 8;
+  for (var i = 0, n = buff.length; i < n; ++i) {
+    var bits = 8;
     if (prefixlen < 8) {
       bits = prefixlen;
     }
@@ -133,10 +134,10 @@ ip.mask = function (addr, mask) {
   addr = ip.toBuffer(addr);
   mask = ip.toBuffer(mask);
 
-  const result = new Buffer(Math.max(addr.length, mask.length));
+  var result = new Buffer(Math.max(addr.length, mask.length));
 
   // Same protocol - do bitwise and
-  let i;
+  var i;
   if (addr.length === mask.length) {
     for (i = 0; i < addr.length; i++) {
       result[i] = addr[i] & mask[i];
@@ -169,30 +170,30 @@ ip.mask = function (addr, mask) {
 };
 
 ip.cidr = function (cidrString) {
-  const cidrParts = cidrString.split('/');
+  var cidrParts = cidrString.split('/');
 
-  const addr = cidrParts[0];
+  var addr = cidrParts[0];
   if (cidrParts.length !== 2) {
     throw new Error(`invalid CIDR subnet: ${addr}`);
   }
 
-  const mask = ip.fromPrefixLen(parseInt(cidrParts[1], 10));
+  var mask = ip.fromPrefixLen(parseInt(cidrParts[1], 10));
 
   return ip.mask(addr, mask);
 };
 
 ip.subnet = function (addr, mask) {
-  const networkAddress = ip.toLong(ip.mask(addr, mask));
+  var networkAddress = ip.toLong(ip.mask(addr, mask));
 
   // Calculate the mask's length.
-  const maskBuffer = ip.toBuffer(mask);
-  let maskLength = 0;
+  var maskBuffer = ip.toBuffer(mask);
+  var maskLength = 0;
 
-  for (let i = 0; i < maskBuffer.length; i++) {
+  for (var i = 0; i < maskBuffer.length; i++) {
     if (maskBuffer[i] === 0xff) {
       maskLength += 8;
     } else {
-      let octet = maskBuffer[i] & 0xff;
+      var octet = maskBuffer[i] & 0xff;
       while (octet) {
         octet = (octet << 1) & 0xff;
         maskLength++;
@@ -200,7 +201,7 @@ ip.subnet = function (addr, mask) {
     }
   }
 
-  const numberOfAddresses = 2 ** (32 - maskLength);
+  var numberOfAddresses = 2 ** (32 - maskLength);
 
   return {
     networkAddress: ip.fromLong(networkAddress),
@@ -223,48 +224,50 @@ ip.subnet = function (addr, mask) {
 };
 
 ip.cidrSubnet = function (cidrString) {
-  const cidrParts = cidrString.split('/');
+  var cidrParts = cidrString.split('/');
 
-  const addr = cidrParts[0];
+  var addr = cidrParts[0];
   if (cidrParts.length !== 2) {
     throw new Error(`invalid CIDR subnet: ${addr}`);
   }
 
-  const mask = ip.fromPrefixLen(parseInt(cidrParts[1], 10));
+  var mask = ip.fromPrefixLen(parseInt(cidrParts[1], 10));
 
   return ip.subnet(addr, mask);
 };
 
 ip.not = function (addr) {
-  const buff = ip.toBuffer(addr);
-  for (let i = 0; i < buff.length; i++) {
+  var buff = ip.toBuffer(addr);
+  for (var i = 0; i < buff.length; i++) {
     buff[i] = 0xff ^ buff[i];
   }
   return ip.toString(buff);
 };
 
 ip.or = function (a, b) {
+  var i;
+
   a = ip.toBuffer(a);
   b = ip.toBuffer(b);
 
   // same protocol
   if (a.length === b.length) {
-    for (let i = 0; i < a.length; ++i) {
+    for (i = 0; i < a.length; ++i) {
       a[i] |= b[i];
     }
     return ip.toString(a);
 
   // mixed protocols
   }
-  let buff = a;
-  let other = b;
+  var buff = a;
+  var other = b;
   if (b.length > a.length) {
     buff = b;
     other = a;
   }
 
-  const offset = buff.length - other.length;
-  for (let i = offset; i < buff.length; ++i) {
+  var offset = buff.length - other.length;
+  for (i = offset; i < buff.length; ++i) {
     buff[i] |= other[i - offset];
   }
 
@@ -272,12 +275,14 @@ ip.or = function (a, b) {
 };
 
 ip.isEqual = function (a, b) {
+  var i;
+
   a = ip.toBuffer(a);
   b = ip.toBuffer(b);
 
   // Same protocol
   if (a.length === b.length) {
-    for (let i = 0; i < a.length; i++) {
+    for (i = 0; i < a.length; i++) {
       if (a[i] !== b[i]) return false;
     }
     return true;
@@ -285,20 +290,20 @@ ip.isEqual = function (a, b) {
 
   // Swap
   if (b.length === 4) {
-    const t = b;
+    var t = b;
     b = a;
     a = t;
   }
 
   // a - IPv4, b - IPv6
-  for (let i = 0; i < 10; i++) {
+  for (i = 0; i < 10; i++) {
     if (b[i] !== 0) return false;
   }
 
-  const word = b.readUInt16BE(10);
+  var word = b.readUInt16BE(10);
   if (word !== 0 && word !== 0xffff) return false;
 
-  for (let i = 0; i < 4; i++) {
+  for (i = 0; i < 4; i++) {
     if (a[i] !== b[i + 12]) return false;
   }
 
@@ -360,7 +365,7 @@ ip.loopback = function (family) {
 //   * undefined: First address with `ipv4` or loopback address `127.0.0.1`.
 //
 ip.address = function (name, family) {
-  const interfaces = os.networkInterfaces();
+  var interfaces = os.networkInterfaces();
 
   //
   // Default to `ipv4`
@@ -372,8 +377,8 @@ ip.address = function (name, family) {
   // return the address.
   //
   if (name && name !== 'private' && name !== 'public') {
-    const res = interfaces[name].filter((details) => {
-      const itemFamily = _normalizeFamily(details.family);
+    var res = interfaces[name].filter((details) => {
+      var itemFamily = _normalizeFamily(details.family);
       return itemFamily === family;
     });
     if (res.length === 0) {
@@ -382,12 +387,12 @@ ip.address = function (name, family) {
     return res[0].address;
   }
 
-  const all = Object.keys(interfaces).map((nic) => {
+  var all = Object.keys(interfaces).map((nic) => {
     //
     // Note: name will only be `public` or `private`
     // when this is called.
     //
-    const addresses = interfaces[nic].filter((details) => {
+    var addresses = interfaces[nic].filter((details) => {
       details.family = _normalizeFamily(details.family);
       if (details.family !== family || ip.isLoopback(details.address)) {
         return false;
@@ -406,7 +411,7 @@ ip.address = function (name, family) {
 };
 
 ip.toLong = function (ip) {
-  let ipl = 0;
+  var ipl = 0;
   ip.split('.').forEach((octet) => {
     ipl <<= 8;
     ipl += parseInt(octet);