diff --git a/lib/net/bip150.js b/lib/net/bip150.js
index a9c2a0f0..f73edeca 100644
--- a/lib/net/bip150.js
+++ b/lib/net/bip150.js
@@ -9,6 +9,7 @@
 'use strict';
 
 var assert = require('assert');
+var path = require('path');
 var EventEmitter = require('events').EventEmitter;
 var util = require('../utils/util');
 var co = require('../utils/co');
@@ -691,7 +692,7 @@ AuthDB.prototype.readKnown = async function readKnown() {
   if (!this.prefix)
     return;
 
-  file = this.prefix + '/known-peers';
+  file = path.join(this.prefix, 'known-peers');
 
   try {
     text = await fs.readFile(file, 'utf8');
@@ -769,7 +770,7 @@ AuthDB.prototype.readAuth = async function readAuth() {
   if (!this.prefix)
     return;
 
-  file = this.prefix + '/authorized-peers';
+  file = path.join(this.prefix, 'authorized-peers');
 
   try {
     text = await fs.readFile(file, 'utf8');
diff --git a/lib/net/hostlist.js b/lib/net/hostlist.js
index 70791ff9..8f0f663a 100644
--- a/lib/net/hostlist.js
+++ b/lib/net/hostlist.js
@@ -7,6 +7,7 @@
 'use strict';
 
 var assert = require('assert');
+var path = require('path');
 var util = require('../utils/util');
 var IP = require('../utils/ip');
 var co = require('../utils/co');
@@ -1634,7 +1635,7 @@ HostListOptions.prototype.fromOptions = function fromOptions(options) {
   if (options.prefix != null) {
     assert(typeof options.prefix === 'string');
     this.prefix = options.prefix;
-    this.filename = this.prefix + '/hosts.json';
+    this.filename = path.join(this.prefix, 'hosts.json');
   }
 
   if (options.filename != null) {
diff --git a/lib/node/config.js b/lib/node/config.js
index 6172bf32..c355ff28 100644
--- a/lib/node/config.js
+++ b/lib/node/config.js
@@ -7,9 +7,10 @@
 'use strict';
 
 var assert = require('assert');
+var path = require('path');
+var os = require('os');
 var fs = require('../utils/fs');
 var util = require('../utils/util');
-var os = require('os');
 var HOME = os.homedir();
 
 /**
@@ -24,10 +25,11 @@ function Config(module) {
     return new Config(module);
 
   assert(typeof module === 'string');
+  assert(module.length > 0);
 
   this.module = module;
   this.network = 'main';
-  this.prefix = HOME + '/.' + module;
+  this.prefix = path.join(HOME, '.' + module);
 
   this.options = Object.create(null);
   this.data = Object.create(null);
@@ -522,7 +524,7 @@ Config.prototype.func = function func(key, fallback) {
  * @returns {String|null}
  */
 
-Config.prototype.path = function path(key, fallback) {
+Config.prototype.path = function _path(key, fallback) {
   var value = this.str(key);
 
   if (fallback === undefined)
@@ -533,16 +535,16 @@ Config.prototype.path = function path(key, fallback) {
 
   switch (value[0]) {
     case '~': // home dir
-      value = HOME + value.substring(1);
+      value = path.join(HOME, value.substring(1));
       break;
     case '@': // prefix
-      value = this.prefix + value.substring(1);
+      value = path.join(this.prefix, value.substring(1));
       break;
     default: // cwd
       break;
   }
 
-  return util.normalize(value);
+  return path.normalize(value);
 };
 
 /**
@@ -593,20 +595,20 @@ Config.prototype.getPrefix = function getPrefix() {
 
   if (prefix) {
     if (prefix[0] === '~')
-      prefix = HOME + prefix.substring(1);
+      prefix = path.join(HOME, prefix.substring(1));
     return prefix;
   }
 
-  prefix = HOME + '/.' + this.module;
+  prefix = path.join(HOME, '.' + this.module);
   network = this.str('network');
 
   if (network) {
     assert(isAlpha(network), 'Bad network.');
     if (network !== 'main')
-      prefix += '/' + network;
+      prefix = path.join(prefix, network);
   }
 
-  return util.normalize(prefix);
+  return path.normalize(prefix);
 };
 
 /**
@@ -617,12 +619,12 @@ Config.prototype.getPrefix = function getPrefix() {
  */
 
 Config.prototype.getFile = function getFile(file) {
-  var path = this.str('config');
+  var name = this.str('config');
 
-  if (path)
-    return path;
+  if (name)
+    return name;
 
-  return this.prefix + '/' + file;
+  return path.join(this.prefix, file);
 };
 
 /**
@@ -644,7 +646,7 @@ Config.prototype.ensure = function ensure() {
  */
 
 Config.prototype.location = function location(file) {
-  return this.prefix + '/' + file;
+  return path.join(this.prefix, file);
 };
 
 /**
diff --git a/lib/utils/encoding.js b/lib/utils/encoding.js
index 40cd71dc..b9c78236 100644
--- a/lib/utils/encoding.js
+++ b/lib/utils/encoding.js
@@ -12,6 +12,7 @@
  */
 
 var BN = require('bn.js');
+var MAX_SAFE_INTEGER = Number.MAX_SAFE_INTEGER;
 var encoding = exports;
 
 /**
@@ -352,7 +353,7 @@ encoding._write64 = function _write64(dst, num, off, be) {
     num -= 1;
   }
 
-  enforce(num <= Number.MAX_SAFE_INTEGER, off, 'Number exceeds 2^53-1');
+  enforce(num <= MAX_SAFE_INTEGER, off, 'Number exceeds 2^53-1');
 
   lo = num % 0x100000000;
   hi = (num - lo) / 0x100000000;
diff --git a/lib/utils/fs.js b/lib/utils/fs.js
index 0ff88b6f..a9a276d6 100644
--- a/lib/utils/fs.js
+++ b/lib/utils/fs.js
@@ -7,6 +7,7 @@
 'use strict';
 
 var fs = require('fs');
+var path = require('path');
 var co = require('./co');
 
 exports.access = co.promisify(fs.access);
@@ -87,11 +88,11 @@ exports.writeFileSync = fs.writeFileSync;
 exports.mkdirpSync = function mkdirpSync(dir, mode) {
   var data = getParts(dir);
   var parts = data.parts;
-  var path = data.path;
+  var path = data.root;
   var i, stat;
 
   if (mode == null)
-    mode = 488; // 0755
+    mode = 0o750;
 
   for (i = 0; i < parts.length; i++) {
     path += parts[i];
@@ -114,11 +115,11 @@ exports.mkdirpSync = function mkdirpSync(dir, mode) {
 exports.mkdirp = async function mkdirp(dir, mode) {
   var data = getParts(dir);
   var parts = data.parts;
-  var path = data.path;
+  var path = data.root;
   var i, stat;
 
   if (mode == null)
-    mode = 488; // 0755
+    mode = 0o750;
 
   for (i = 0; i < parts.length; i++) {
     path += parts[i];
@@ -139,28 +140,28 @@ exports.mkdirp = async function mkdirp(dir, mode) {
 };
 
 function getParts(path) {
+  var root = '';
   var parts;
 
   path = path.replace(/\\/g, '/');
   path = path.replace(/(^|\/)\.\//, '$1');
   path = path.replace(/\/+\.?$/, '');
   parts = path.split(/\/+/);
-  path = '';
 
   if (process.platform === 'win32') {
     if (parts[0].indexOf(':') !== -1)
-      path = parts.shift() + '/';
+      root = parts.shift() + '/';
   }
 
   if (parts.length > 0) {
     if (parts[0].length === 0) {
       parts.shift();
-      path = '/';
+      root = '/';
     }
   }
 
   return {
-    path: path,
+    root: root,
     parts: parts
   };
 }
diff --git a/lib/utils/util.js b/lib/utils/util.js
index 1313c75b..c113f5b3 100644
--- a/lib/utils/util.js
+++ b/lib/utils/util.js
@@ -792,26 +792,6 @@ util.binaryRemove = function binaryRemove(items, item, compare) {
   return true;
 };
 
-/**
- * Normalize a path.
- * @param {String} path
- * @param {Boolean?} dirname
- */
-
-util.normalize = function normalize(path, dirname) {
-  var parts;
-
-  path = path.replace(/\\/g, '/');
-  path = path.replace(/(^|\/)\.\//, '$1');
-  path = path.replace(/\/+\.?$/, '');
-  parts = path.split(/\/+/);
-
-  if (dirname)
-    parts.pop();
-
-  return parts.join('/');
-};
-
 /**
  * Ensure hidden-class mode for object.
  * @param {Object} obj
@@ -850,24 +830,6 @@ if (!''.startsWith) {
   };
 }
 
-/**
- * Promisify a function.
- * @param {Function} func
- * @returns {Function}
- */
-
-util.promisify = function promisify(func) {
-  return function() {
-    var result;
-    try {
-      result = func.apply(this, arguments);
-    } catch (e) {
-      return Promise.reject(e);
-    }
-    return Promise.resolve(result);
-  };
-};
-
 /**
  * Get memory usage info.
  * @returns {Object}