diff --git a/lib/bip70/paymentrequest.js b/lib/bip70/paymentrequest.js
index 6af79337d..c954704cc 100644
--- a/lib/bip70/paymentrequest.js
+++ b/lib/bip70/paymentrequest.js
@@ -161,10 +161,10 @@ PaymentRequest.prototype.getAlgorithm = function getAlgorithm() {
     throw new Error('Could not parse PKI algorithm.');
 
   if (parts[0] !== 'x509')
-    throw new Error('Unknown PKI type: ' + parts[0]);
+    throw new Error(`Unknown PKI type: ${parts[0]}.`);
 
   if (parts[1] !== 'sha1' && parts[1] !== 'sha256')
-    throw new Error('Unknown hash algorithm: ' + parts[1]);
+    throw new Error(`Unknown hash algorithm: ${parts[1]}.`);
 
   return new Algorithm(parts[0], parts[1]);
 };
diff --git a/lib/bip70/x509.js b/lib/bip70/x509.js
index 917e168e3..4620caec9 100644
--- a/lib/bip70/x509.js
+++ b/lib/bip70/x509.js
@@ -189,7 +189,7 @@ x509.getKeyAlgorithm = function getKeyAlgorithm(cert) {
   let alg = x509.oid[oid];
 
   if (!alg)
-    throw new Error('Unknown key algorithm: ' + oid);
+    throw new Error(`Unknown key algorithm: ${oid}.`);
 
   return alg;
 };
@@ -205,7 +205,7 @@ x509.getSigAlgorithm = function getSigAlgorithm(cert) {
   let alg = x509.oid[oid];
 
   if (!alg || !alg.hash)
-    throw new Error('Unknown signature algorithm: ' + oid);
+    throw new Error(`Unknown signature algorithm: ${oid}.`);
 
   return alg;
 };
@@ -228,7 +228,7 @@ x509.getCurve = function getCurve(params) {
   curve = x509.curves[oid];
 
   if (!curve)
-    throw new Error('Unknown ECDSA curve: ' + oid);
+    throw new Error(`Unknown ECDSA curve: ${oid}.`);
 
   return curve;
 };
@@ -457,7 +457,7 @@ x509.verifyChain = function verifyChain(certs) {
     let sig = child.sig;
 
     if (!pk.verify(alg.hash, msg, sig, key))
-      throw new Error(alg.key + ' verification failed for chain.');
+      throw new Error(`${alg.key} verification failed for chain.`);
   }
 
   // Make sure we trust one
diff --git a/lib/blockchain/chaindb.js b/lib/blockchain/chaindb.js
index 84b6d6e2f..61084286d 100644
--- a/lib/blockchain/chaindb.js
+++ b/lib/blockchain/chaindb.js
@@ -712,7 +712,7 @@ ChainDB.prototype.prune = async function prune(tip) {
     let hash = await this.getHash(i);
 
     if (!hash)
-      throw new Error('Cannot find hash for ' + i);
+      throw new Error(`Cannot find hash for ${i}.`);
 
     batch.del(layout.b(hash));
     batch.del(layout.u(hash));
diff --git a/lib/btc/amount.js b/lib/btc/amount.js
index 2ec2cbff9..0d9171363 100644
--- a/lib/btc/amount.js
+++ b/lib/btc/amount.js
@@ -120,7 +120,7 @@ Amount.prototype.to = function to(unit, num) {
     case 'btc':
       return this.toBTC(num);
   }
-  throw new Error('Unknown unit "' + unit + '".');
+  throw new Error(`Unknown unit "${unit}".`);
 };
 
 /**
@@ -218,7 +218,7 @@ Amount.prototype.from = function from(unit, value, num) {
     case 'btc':
       return this.fromBTC(value, num);
   }
-  throw new Error('Unknown unit "' + unit + '".');
+  throw new Error(`Unknown unit "${unit}".`);
 };
 
 /**
diff --git a/lib/crypto/pbkdf2-browser.js b/lib/crypto/pbkdf2-browser.js
index e824d9f66..a2407f482 100644
--- a/lib/crypto/pbkdf2-browser.js
+++ b/lib/crypto/pbkdf2-browser.js
@@ -98,6 +98,6 @@ function getHash(name) {
     case 'sha512':
       return 'SHA-512';
     default:
-      throw new Error('Algorithm not supported: ' + name);
+      throw new Error(`Algorithm not supported: ${name}.`);
   }
 }
diff --git a/lib/db/backends.js b/lib/db/backends.js
index fc7bee74d..0f589764e 100644
--- a/lib/db/backends.js
+++ b/lib/db/backends.js
@@ -18,11 +18,11 @@ exports.get = function get(name) {
       case 'memory':
         return require('./memdb');
       default:
-        throw new Error('Database backend "' + name + '" not found.');
+        throw new Error(`Database backend "${name}" not found.`);
     }
   } catch (e) {
     if (e.code === 'MODULE_NOT_FOUND')
-      throw new Error('Database backend "' + name + '" not found.');
+      throw new Error(`Database backend "${name}" not found.`);
     throw e;
   }
 };
diff --git a/lib/hd/wordlist-browser.js b/lib/hd/wordlist-browser.js
index 258784e98..f77898527 100644
--- a/lib/hd/wordlist-browser.js
+++ b/lib/hd/wordlist-browser.js
@@ -25,6 +25,6 @@ exports.get = function get(name) {
     case 'spanish':
       return words.spanish;
     default:
-      throw new Error('Unknown language: ' + name);
+      throw new Error(`Unknown language: ${name}.`);
   }
 };
diff --git a/lib/hd/wordlist.js b/lib/hd/wordlist.js
index 001f8569d..379fbce3c 100644
--- a/lib/hd/wordlist.js
+++ b/lib/hd/wordlist.js
@@ -23,6 +23,6 @@ exports.get = function get(name) {
     case 'spanish':
       return require('./words/spanish.js');
     default:
-      throw new Error('Unknown language: ' + name);
+      throw new Error(`Unknown language: ${name}.`);
   }
 };
diff --git a/lib/http/base.js b/lib/http/base.js
index e8e730ddd..4268ce57c 100644
--- a/lib/http/base.js
+++ b/lib/http/base.js
@@ -68,10 +68,9 @@ HTTPBase.prototype._init = function _init() {
   this.server.on('connection', (socket) => {
     socket.on('error', (err) => {
       if (err.message === 'Parse Error') {
-        let msg = 'http_parser.execute failure (';
-        msg += 'parsed=' + (err.bytesParsed || -1);
-        msg += ' code=' + err.code;
-        msg += ')';
+        let msg = 'http_parser.execute failure';
+        msg += ` (parsed=${err.bytesParsed || -1}`;
+        msg += ` code=${err.code})`;
         err = new Error(msg);
       }
 
@@ -134,7 +133,7 @@ HTTPBase.prototype.handleRequest = async function handleRequest(req, res) {
   routes = this.routes.getHandlers(req.method);
 
   if (!routes)
-    throw new Error('No routes found for method: ' + req.method);
+    throw new Error(`No routes found for method: ${req.method}.`);
 
   for (let route of routes) {
     let params = route.match(req.pathname);
@@ -151,7 +150,7 @@ HTTPBase.prototype.handleRequest = async function handleRequest(req, res) {
       return;
   }
 
-  throw new Error('No routes found for path: ' + req.pathname);
+  throw new Error(`No routes found for path: ${req.pathname}.`);
 };
 
 /**
diff --git a/lib/http/request.js b/lib/http/request.js
index 2d74ac05a..433c66375 100644
--- a/lib/http/request.js
+++ b/lib/http/request.js
@@ -602,7 +602,7 @@ function getType(type) {
     case 'bin':
       return 'application/octet-stream';
     default:
-      throw new Error('Unknown type: ' + type);
+      throw new Error(`Unknown type: ${type}.`);
   }
 }
 
diff --git a/lib/http/rpc.js b/lib/http/rpc.js
index b3376a072..9c00f1bb1 100644
--- a/lib/http/rpc.js
+++ b/lib/http/rpc.js
@@ -1355,7 +1355,7 @@ RPC.prototype._createTemplate = async function _createTemplate(maxVersion, coinb
         if (!deploy.force) {
           if (!rules || rules.indexOf(name) === -1) {
             throw new RPCError(errs.INVALID_PARAMETER,
-              'Client must support ' + name + '.');
+              `Client must support ${name}.`);
           }
           name = '!' + name;
         }
@@ -2398,7 +2398,7 @@ RPC.prototype._addBlock = async function _addBlock(block) {
     if (err.type === 'VerifyError') {
       this.logger.warning('RPC block rejected: %s (%s).',
         block.rhash(), err.reason);
-      return 'rejected: ' + err.reason;
+      return `rejected: ${err.reason}`;
     }
     throw err;
   }
diff --git a/lib/http/rpcbase.js b/lib/http/rpcbase.js
index a5fc15bc0..382294bc0 100644
--- a/lib/http/rpcbase.js
+++ b/lib/http/rpcbase.js
@@ -253,7 +253,7 @@ RPCBase.prototype.execute = async function execute(json, help) {
         return await mount.execute(json, help);
     }
     throw new RPCError(RPCBase.errors.METHOD_NOT_FOUND,
-      'Method not found: ' + json.method + '.');
+      `Method not found: ${json.method}.`);
   }
 
   return await func.call(this, json.params, help);
diff --git a/lib/http/server.js b/lib/http/server.js
index f627e659b..2c6c10666 100644
--- a/lib/http/server.js
+++ b/lib/http/server.js
@@ -8,6 +8,7 @@
 'use strict';
 
 const assert = require('assert');
+const path = require('path');
 const HTTPBase = require('./base');
 const util = require('../utils/util');
 const base58 = require('../utils/base58');
@@ -774,8 +775,8 @@ HTTPOptions.prototype.fromOptions = function fromOptions(options) {
   if (options.prefix != null) {
     assert(typeof options.prefix === 'string');
     this.prefix = options.prefix;
-    this.keyFile = this.prefix + '/key.pem';
-    this.certFile = this.prefix + '/cert.pem';
+    this.keyFile = path.join(this.prefix, 'key.pem');
+    this.certFile = path.join(this.prefix, 'cert.pem');
   }
 
   if (options.host != null) {
diff --git a/lib/mempool/mempool.js b/lib/mempool/mempool.js
index b3b13e423..c6c8e191a 100644
--- a/lib/mempool/mempool.js
+++ b/lib/mempool/mempool.js
@@ -7,6 +7,7 @@
 'use strict';
 
 const assert = require('assert');
+const path = require('path');
 const AsyncObject = require('../utils/asyncobject');
 const common = require('../blockchain/common');
 const policy = require('../protocol/policy');
@@ -2057,7 +2058,7 @@ MempoolOptions.prototype.fromOptions = function fromOptions(options) {
   if (options.prefix != null) {
     assert(typeof options.prefix === 'string');
     this.prefix = options.prefix;
-    this.location = this.prefix + '/mempool';
+    this.location = path.join(this.prefix, 'mempool');
   }
 
   if (options.location != null) {
diff --git a/lib/net/bip150.js b/lib/net/bip150.js
index 39c078000..36905e40f 100644
--- a/lib/net/bip150.js
+++ b/lib/net/bip150.js
@@ -417,7 +417,7 @@ BIP150.prototype._wait = function wait(timeout, resolve, reject) {
   this.job = co.job(resolve, reject);
 
   if (this.outbound && !this.peerIdentity) {
-    this.reject(new Error('No identity for ' + this.hostname + '.'));
+    this.reject(new Error(`No identity for ${this.hostname}.`));
     return;
   }
 
@@ -729,7 +729,7 @@ AuthDB.prototype.parseKnown = function parseKnown(text) {
     key = Buffer.from(key, 'hex');
 
     if (key.length !== 33)
-      throw new Error('Invalid key: ' + parts[1]);
+      throw new Error(`Invalid key: ${parts[1]}.`);
 
     if (host && host.length > 0)
       this.addKnown(host, key);
@@ -792,7 +792,7 @@ AuthDB.prototype.parseAuth = function parseAuth(text) {
     key = Buffer.from(line, 'hex');
 
     if (key.length !== 33)
-      throw new Error('Invalid key: ' + line);
+      throw new Error(`Invalid key: ${line}.`);
 
     this.addAuthorized(key);
   }
diff --git a/lib/net/common.js b/lib/net/common.js
index 802b3270a..fda0005ea 100644
--- a/lib/net/common.js
+++ b/lib/net/common.js
@@ -134,7 +134,7 @@ exports.REQUIRED_SERVICES = 0
  * @default
  */
 
-exports.USER_AGENT = '/bcoin:' + pkg.version + '/';
+exports.USER_AGENT = `/bcoin:${pkg.version}/`;
 
 /**
  * Max message size (~4mb with segwit, formerly 2mb)
diff --git a/lib/net/peer.js b/lib/net/peer.js
index daea99aa5..e497c9765 100644
--- a/lib/net/peer.js
+++ b/lib/net/peer.js
@@ -1419,10 +1419,10 @@ Peer.prototype.error = function error(err) {
     msg = err.code;
     err = new Error(msg);
     err.code = msg;
-    err.message = 'Socket Error: ' + msg;
+    err.message = `Socket Error: ${msg}`;
   }
 
-  err.message += ' (' + this.hostname() + ')';
+  err.message += ` (${this.hostname()})`;
 
   this.emit('error', err);
 };
diff --git a/lib/net/socks.js b/lib/net/socks.js
index fe088ad8a..86852dbe0 100644
--- a/lib/net/socks.js
+++ b/lib/net/socks.js
@@ -735,7 +735,7 @@ function parseAddr(data, offset) {
       port = br.readU16BE();
       break;
     default:
-      throw new Error('Unknown SOCKS address type: ' + type + '.');
+      throw new Error(`Unknown SOCKS address type: ${type}.`);
   }
 
   return {
diff --git a/lib/net/upnp.js b/lib/net/upnp.js
index 5c2d62e51..df25f3b27 100644
--- a/lib/net/upnp.js
+++ b/lib/net/upnp.js
@@ -688,7 +688,7 @@ function findError(el) {
   if (cdesc)
     desc = cdesc.text;
 
-  return new Error('UPnPError: ' + desc + ' (' + code + ')');
+  return new Error(`UPnPError: ${desc} (${code}).`);
 }
 
 /*
diff --git a/lib/node/config.js b/lib/node/config.js
index 332c2fc24..f90d19dd1 100644
--- a/lib/node/config.js
+++ b/lib/node/config.js
@@ -259,7 +259,7 @@ Config.prototype.str = function str(key, fallback) {
     return fallback;
 
   if (typeof value !== 'string')
-    throw new Error(key + ' must be a string.');
+    throw new Error(`${key} must be a string.`);
 
   return value;
 };
@@ -282,17 +282,17 @@ Config.prototype.num = function num(key, fallback) {
 
   if (typeof value !== 'string') {
     if (typeof value !== 'number')
-      throw new Error(key + ' must be a positive integer.');
+      throw new Error(`${key} must be a positive integer.`);
     return value;
   }
 
   if (!/^\d+$/.test(value))
-    throw new Error(key + ' must be a positive integer.');
+    throw new Error(`${key} must be a positive integer.`);
 
   value = parseInt(value, 10);
 
   if (!isFinite(value))
-    throw new Error(key + ' must be a positive integer.');
+    throw new Error(`${key} must be a positive integer.`);
 
   return value;
 };
@@ -315,17 +315,17 @@ Config.prototype.flt = function flt(key, fallback) {
 
   if (typeof value !== 'string') {
     if (typeof value !== 'number')
-      throw new Error(key + ' must be a float.');
+      throw new Error(`${key} must be a float.`);
     return value;
   }
 
   if (!/^\d*(?:\.\d*)?$/.test(value))
-    throw new Error(key + ' must be a float.');
+    throw new Error(`${key} must be a float.`);
 
   value = parseFloat(value);
 
   if (!isFinite(value))
-    throw new Error(key + ' must be a float.');
+    throw new Error(`${key} must be a float.`);
 
   return value;
 };
@@ -348,22 +348,22 @@ Config.prototype.amt = function amt(key, fallback) {
 
   if (typeof value !== 'string') {
     if (typeof value !== 'number')
-      throw new Error(key + ' must be an amount.');
+      throw new Error(`${key} must be an amount.`);
     return value;
   }
 
   if (!/^\d+(\.\d{0,8})?$/.test(value))
-    throw new Error(key + ' must be an amount.');
+    throw new Error(`${key} must be an amount.`);
 
   value = parseFloat(value);
 
   if (!isFinite(value))
-    throw new Error(key + ' must be an amount.');
+    throw new Error(`${key} must be an amount.`);
 
   value *= 1e8;
 
   if (value % 1 !== 0 || value < 0 || value > 0x1fffffffffffff)
-    throw new Error(key + ' must be an amount (uint64).');
+    throw new Error(`${key} must be an amount (uint64).`);
 
   return value;
 };
@@ -386,7 +386,7 @@ Config.prototype.bool = function bool(key, fallback) {
 
   if (typeof value !== 'string') {
     if (typeof value !== 'boolean')
-      throw new Error(key + ' must be a boolean.');
+      throw new Error(`${key} must be a boolean.`);
     return value;
   }
 
@@ -396,7 +396,7 @@ Config.prototype.bool = function bool(key, fallback) {
   if (value === 'false' || value === '0')
     return false;
 
-  throw new Error(key + ' must be a boolean.');
+  throw new Error(`${key} must be a boolean.`);
 };
 
 /**
@@ -418,14 +418,14 @@ Config.prototype.buf = function buf(key, fallback) {
 
   if (typeof value !== 'string') {
     if (!Buffer.isBuffer(value))
-      throw new Error(key + ' must be a buffer.');
+      throw new Error(`${key} must be a buffer.`);
     return value;
   }
 
   data = Buffer.from(value, 'hex');
 
   if (data.length !== value.length / 2)
-    throw new Error(key + ' must be a hex string.');
+    throw new Error(`${key} must be a hex string.`);
 
   return data;
 };
@@ -449,7 +449,7 @@ Config.prototype.array = function array(key, fallback) {
 
   if (typeof value !== 'string') {
     if (!Array.isArray(value))
-      throw new Error(key + ' must be an array.');
+      throw new Error(`${key} must be an array.`);
     return value;
   }
 
@@ -483,7 +483,7 @@ Config.prototype.obj = function obj(key, fallback) {
     return fallback;
 
   if (!value || typeof value !== 'object')
-    throw new Error(key + ' must be an object.');
+    throw new Error(`${key} must be an object.`);
 
   return value;
 };
@@ -505,7 +505,7 @@ Config.prototype.func = function func(key, fallback) {
     return fallback;
 
   if (!value || typeof value !== 'function')
-    throw new Error(key + ' must be a function.');
+    throw new Error(`${key} must be a function.`);
 
   return value;
 };
diff --git a/lib/node/node.js b/lib/node/node.js
index c0a5f5208..bf73eff39 100644
--- a/lib/node/node.js
+++ b/lib/node/node.js
@@ -298,11 +298,11 @@ Node.prototype.use = function use(plugin) {
       case 'mempool':
       case 'miner':
       case 'pool':
-        assert(false, plugin.id + ' is already added.');
+        assert(false, `${plugin.id} is already added.`);
         break;
     }
 
-    assert(!this.plugins[plugin.id], plugin.id + ' is already added.');
+    assert(!this.plugins[plugin.id], `${plugin.id} is already added.`);
 
     this.plugins[plugin.id] = instance;
   }
@@ -355,7 +355,7 @@ Node.prototype.require = function require(name) {
   }
 
   plugin = this.plugins[name];
-  assert(plugin, name + ' is not loaded.');
+  assert(plugin, `${name} is not loaded.`);
 
   return plugin;
 };
diff --git a/lib/primitives/mtx.js b/lib/primitives/mtx.js
index f091d53e0..3d3340acf 100644
--- a/lib/primitives/mtx.js
+++ b/lib/primitives/mtx.js
@@ -1597,7 +1597,7 @@ CoinSelector.prototype.init = function init(coins) {
       this.coins.sort(sortValue);
       break;
     default:
-      throw new FundingError('Bad selection type: ' + this.selection);
+      throw new FundingError(`Bad selection type: ${this.selection}.`);
   }
 };
 
@@ -1812,8 +1812,8 @@ function FundingError(msg, available, required) {
   this.requiredFunds = -1;
 
   if (available != null) {
-    this.message += ' (available=' + Amount.btc(available) + ',';
-    this.message += ' required=' + Amount.btc(required) + ')';
+    this.message += ` (available=${Amount.btc(available)},`;
+    this.message += ` required=${Amount.btc(required)})`;
     this.availableFunds = available;
     this.requiredFunds = required;
   }
diff --git a/lib/protocol/network.js b/lib/protocol/network.js
index 36019300d..b6e89783f 100644
--- a/lib/protocol/network.js
+++ b/lib/protocol/network.js
@@ -245,7 +245,7 @@ Network.by = function by(value, compare, network, name) {
     network = Network.get(network);
     if (compare(network, value))
       return network;
-    throw new Error('Network mismatch for ' + name + '.');
+    throw new Error(`Network mismatch for ${name}.`);
   }
 
   for (let type of networks.types) {
@@ -254,7 +254,7 @@ Network.by = function by(value, compare, network, name) {
       return Network.get(type);
   }
 
-  throw new Error('Network not found for ' + name + '.');
+  throw new Error(`Network not found for ${name}.`);
 };
 
 /**
@@ -360,7 +360,7 @@ Network.prototype.toString = function toString() {
  */
 
 Network.prototype.inspect = function inspect() {
-  return '<Network: ' + this.type + '>';
+  return `<Network: ${this.type}>`;
 };
 
 /**
diff --git a/lib/script/scriptnum.js b/lib/script/scriptnum.js
index 89151ea30..f4c8278e9 100644
--- a/lib/script/scriptnum.js
+++ b/lib/script/scriptnum.js
@@ -154,7 +154,7 @@ ScriptNum.prototype.toString = function toString(base) {
     return str;
   }
 
-  assert(false, 'Base ' + base + ' not supported.');
+  assert(false, `Base ${base} not supported.`);
 };
 
 ScriptNum.prototype.toJSON = function toJSON() {
@@ -236,7 +236,7 @@ ScriptNum.prototype.fromString = function fromString(str, base) {
     return this;
   }
 
-  assert(false, 'Base ' + base + ' not supported.');
+  assert(false, `Base ${base} not supported.`);
 };
 
 ScriptNum.fromString = function fromString(str, base) {
diff --git a/lib/utils/asn1.js b/lib/utils/asn1.js
index f8dcbe348..cde6e0ced 100644
--- a/lib/utils/asn1.js
+++ b/lib/utils/asn1.js
@@ -127,7 +127,7 @@ ASN1.readSeq = function readSeq(br) {
 ASN1.implicit = function implicit(br, type) {
   let tag = ASN1.readTag(br);
   if (tag.type !== type)
-    throw new Error('Unexpected tag: ' + tag.type + '.');
+    throw new Error(`Unexpected tag: ${tag.type}.`);
   return tag;
 };
 
@@ -232,7 +232,7 @@ ASN1.readString = function readString(br) {
     case 0x1e: // bmpstr
       return br.readString('utf8', tag.size);
     default:
-      throw new Error('Unexpected tag: ' + tag.type + '.');
+      throw new Error(`Unexpected tag: ${tag.type}.`);
   }
 };
 
@@ -393,7 +393,7 @@ ASN1.readTime = function readTime(br) {
       sec = str.slice(12, 14) | 0;
       break;
     default:
-      throw new Error('Unexpected tag: ' + tag.type + '.');
+      throw new Error(`Unexpected tag: ${tag.type}.`);
   }
 
   return Date.UTC(year, mon - 1, day, hour, min, sec, 0) / 1000;
diff --git a/lib/utils/asyncemitter.js b/lib/utils/asyncemitter.js
index afe5c9f9e..3e6c18f3f 100644
--- a/lib/utils/asyncemitter.js
+++ b/lib/utils/asyncemitter.js
@@ -235,7 +235,7 @@ AsyncEmitter.prototype.emit = function emit(type) {
       if (error instanceof Error)
         throw error;
 
-      err = new Error('Uncaught, unspecified "error" event. (' + error + ')');
+      err = new Error(`Uncaught, unspecified "error" event. (${error})`);
       err.context = error;
       throw err;
     }
@@ -298,7 +298,7 @@ AsyncEmitter.prototype.fire = async function fire(type) {
       if (error instanceof Error)
         throw error;
 
-      err = new Error('Uncaught, unspecified "error" event. (' + error + ')');
+      err = new Error(`Uncaught, unspecified "error" event. (${error})`);
       err.context = error;
       throw err;
     }
diff --git a/lib/utils/co.js b/lib/utils/co.js
index 95068ea0a..a3ef99cc6 100644
--- a/lib/utils/co.js
+++ b/lib/utils/co.js
@@ -165,7 +165,7 @@ function callbackify(func) {
 
     if (args.length === 0
         || typeof args[args.length - 1] !== 'function') {
-      throw new Error((func.name || 'Function') + ' requires a callback.');
+      throw new Error(`${func.name || 'Function'} requires a callback.`);
     }
 
     callback = args.pop();
diff --git a/lib/utils/encoding.js b/lib/utils/encoding.js
index 7e142efc1..ee77ba8e5 100644
--- a/lib/utils/encoding.js
+++ b/lib/utils/encoding.js
@@ -1037,7 +1037,7 @@ encoding.EncodingError = function EncodingError(offset, reason) {
     Error.captureStackTrace(this, EncodingError);
 
   this.type = 'EncodingError';
-  this.message = reason + ' (offset=' + offset + ').';
+  this.message = `${reason} (offset=${offset}).`;
 };
 
 inherits(encoding.EncodingError, Error);
diff --git a/lib/utils/ip.js b/lib/utils/ip.js
index 5e8550906..63e561789 100644
--- a/lib/utils/ip.js
+++ b/lib/utils/ip.js
@@ -440,7 +440,7 @@ IP.toString = function toString(raw) {
     return host;
   }
 
-  throw new Error('Invalid IP address: ' + raw.toString('hex'));
+  throw new Error(`Invalid IP address: ${raw.toString('hex')}.`);
 };
 
 /**
diff --git a/lib/utils/validator.js b/lib/utils/validator.js
index 1cb3f7657..7982377d0 100644
--- a/lib/utils/validator.js
+++ b/lib/utils/validator.js
@@ -87,7 +87,7 @@ Validator.prototype.get = function get(key, fallback) {
     let value;
 
     if (!map || typeof map !== 'object')
-      throw new ValidationError('Data is not an object.');
+      throw new ValidationError('data', 'object');
 
     value = map[key];
 
@@ -115,7 +115,7 @@ Validator.prototype.str = function str(key, fallback) {
     return fallback;
 
   if (typeof value !== 'string')
-    throw new ValidationError(fmt(key) + ' must be a string.');
+    throw new ValidationError(key, 'number');
 
   return value;
 };
@@ -138,17 +138,17 @@ Validator.prototype.num = function num(key, fallback) {
 
   if (typeof value !== 'string') {
     if (typeof value !== 'number')
-      throw new ValidationError(fmt(key) + ' must be a number.');
+      throw new ValidationError(key, 'number');
     return value;
   }
 
   if (!/^\d+$/.test(value))
-    throw new ValidationError(fmt(key) + ' must be a number.');
+    throw new ValidationError(key, 'number');
 
   value = parseInt(value, 10);
 
   if (!isFinite(value))
-    throw new ValidationError(fmt(key) + ' must be a number.');
+    throw new ValidationError(key, 'number');
 
   return value;
 };
@@ -171,17 +171,17 @@ Validator.prototype.flt = function flt(key, fallback) {
 
   if (typeof value !== 'string') {
     if (typeof value !== 'number')
-      throw new ValidationError(fmt(key) + ' must be a float.');
+      throw new ValidationError(key, 'float');
     return value;
   }
 
   if (!/^\d*(?:\.\d*)?$/.test(value))
-    throw new ValidationError(fmt(key) + ' must be a float.');
+    throw new ValidationError(key, 'float');
 
   value = parseFloat(value);
 
   if (!isFinite(value))
-    throw new ValidationError(fmt(key) + ' must be a float.');
+    throw new ValidationError(key, 'float');
 
   return value;
 };
@@ -203,7 +203,7 @@ Validator.prototype.u32 = function u32(key, fallback) {
     return fallback;
 
   if ((value >>> 0) !== value)
-    throw new ValidationError(fmt(key) + ' must be a uint32.');
+    throw new ValidationError(key, 'uint32');
 
   return value;
 };
@@ -225,7 +225,7 @@ Validator.prototype.u64 = function u64(key, fallback) {
     return fallback;
 
   if (value % 1 !== 0 || value < 0 || value > 0x1fffffffffffff)
-    throw new ValidationError(fmt(key) + ' must be a uint64.');
+    throw new ValidationError(key, 'uint64');
 
   return value;
 };
@@ -247,7 +247,7 @@ Validator.prototype.i32 = function i32(key, fallback) {
     return fallback;
 
   if ((value | 0) !== value)
-    throw new ValidationError(fmt(key) + ' must be an int32.');
+    throw new ValidationError(key, 'int32');
 
   return value;
 };
@@ -269,7 +269,7 @@ Validator.prototype.i64 = function i64(key, fallback) {
     return fallback;
 
   if (value % 1 !== 0 || Math.abs(value) > 0x1fffffffffffff)
-    throw new ValidationError(fmt(key) + ' must be an int64.');
+    throw new ValidationError(key, 'int64');
 
   return value;
 };
@@ -292,22 +292,22 @@ Validator.prototype.amt = function amt(key, fallback) {
 
   if (typeof value !== 'string') {
     if (typeof value !== 'number')
-      throw new ValidationError(fmt(key) + ' must be an amount.');
+      throw new ValidationError(key, 'amount');
     return value;
   }
 
   if (!/^\d+(\.\d{0,8})?$/.test(value))
-    throw new ValidationError(fmt(key) + ' must be an amount.');
+    throw new ValidationError(key, 'amount');
 
   value = parseFloat(value);
 
   if (!isFinite(value))
-    throw new ValidationError(fmt(key) + ' must be an amount.');
+    throw new ValidationError(key, 'amount');
 
   value *= 1e8;
 
   if (value % 1 !== 0 || value < 0 || value > 0x1fffffffffffff)
-    throw new ValidationError(fmt(key) + ' must be an amount (uint64).');
+    throw new ValidationError(key, 'amount (uint64)');
 
   return value;
 };
@@ -331,7 +331,7 @@ Validator.prototype.btc = function btc(key, fallback) {
   value *= 1e8;
 
   if (value % 1 !== 0 || value < 0 || value > 0x1fffffffffffff)
-    throw new ValidationError(fmt(key) + ' must be a btc float (uint64).');
+    throw new ValidationError(key, 'btc float (uint64)');
 
   return value;
 };
@@ -355,19 +355,19 @@ Validator.prototype.hash = function hash(key, fallback) {
 
   if (typeof value !== 'string') {
     if (!Buffer.isBuffer(value))
-      throw new ValidationError(fmt(key) + ' must be a hash.');
+      throw new ValidationError(key, 'hash');
 
     if (value.length !== 32)
-      throw new ValidationError(fmt(key) + ' must be a hash.');
+      throw new ValidationError(key, 'hash');
 
     return value.toString('hex');
   }
 
   if (value.length !== 64)
-    throw new ValidationError(fmt(key) + ' must be a hex string.');
+    throw new ValidationError(key, 'hex string');
 
   if (!/^[0-9a-f]+$/i.test(value))
-    throw new ValidationError(fmt(key) + ' must be a hex string.');
+    throw new ValidationError(key, 'hex string');
 
   for (let i = 0; i < value.length; i += 2)
     out = value.slice(i, i + 2) + out;
@@ -413,7 +413,7 @@ Validator.prototype.numstr = function numstr(key, fallback) {
 
   if (typeof value !== 'string') {
     if (typeof value !== 'number')
-      throw new ValidationError(fmt(key) + ' must be a number or string.');
+      throw new ValidationError(key, 'number or string');
     return value;
   }
 
@@ -451,7 +451,7 @@ Validator.prototype.bool = function bool(key, fallback) {
 
   if (typeof value !== 'string') {
     if (typeof value !== 'boolean')
-      throw new ValidationError(fmt(key) + ' must be a boolean.');
+      throw new ValidationError(key, 'boolean');
     return value;
   }
 
@@ -461,7 +461,7 @@ Validator.prototype.bool = function bool(key, fallback) {
   if (value === 'false' || value === '0')
     return false;
 
-  throw new ValidationError(fmt(key) + ' must be a boolean.');
+  throw new ValidationError(key, 'boolean');
 };
 
 /**
@@ -487,14 +487,14 @@ Validator.prototype.buf = function buf(key, fallback, enc) {
 
   if (typeof value !== 'string') {
     if (!Buffer.isBuffer(value))
-      throw new ValidationError(fmt(key) + ' must be a buffer.');
+      throw new ValidationError(key, 'buffer');
     return value;
   }
 
   data = Buffer.from(value, enc);
 
   if (data.length !== Buffer.byteLength(value, enc))
-    throw new ValidationError(fmt(key) + ' must be a ' + enc + ' string.');
+    throw new ValidationError(key, `${enc} string`);
 
   return data;
 };
@@ -518,7 +518,7 @@ Validator.prototype.array = function array(key, fallback) {
 
   if (typeof value !== 'string') {
     if (!Array.isArray(value))
-      throw new ValidationError(fmt(key) + ' must be a list/array.');
+      throw new ValidationError(key, 'list/array');
     return value;
   }
 
@@ -552,7 +552,7 @@ Validator.prototype.obj = function obj(key, fallback) {
     return fallback;
 
   if (!value || typeof value !== 'object')
-    throw new ValidationError(fmt(key) + ' must be an object.');
+    throw new ValidationError(key, 'object');
 
   return value;
 };
@@ -574,7 +574,7 @@ Validator.prototype.func = function func(key, fallback) {
     return fallback;
 
   if (typeof value !== 'function')
-    throw new ValidationError(fmt(key) + ' must be a function.');
+    throw new ValidationError(key, 'function');
 
   return value;
 };
@@ -598,14 +598,14 @@ function inherits(child, parent) {
   });
 }
 
-function ValidationError(msg) {
+function ValidationError(key, type) {
   Error.call(this);
 
   if (Error.captureStackTrace)
     Error.captureStackTrace(this, ValidationError);
 
   this.type = 'ValidationError';
-  this.message = msg;
+  this.message = `${fmt(key)} must be a ${type}.`
 }
 
 inherits(ValidationError, Error);
diff --git a/lib/wallet/account.js b/lib/wallet/account.js
index 67c58916c..24cc5e669 100644
--- a/lib/wallet/account.js
+++ b/lib/wallet/account.js
@@ -454,7 +454,7 @@ Account.prototype.createKey = async function createKey(branch) {
       this.nested = key;
       break;
     default:
-      throw new Error('Bad branch: ' + branch);
+      throw new Error(`Bad branch: ${branch}.`);
   }
 
   this.save();
diff --git a/lib/wallet/masterkey.js b/lib/wallet/masterkey.js
index 5739eec41..6cc158da1 100644
--- a/lib/wallet/masterkey.js
+++ b/lib/wallet/masterkey.js
@@ -267,7 +267,7 @@ MasterKey.prototype.derive = async function derive(passwd) {
     case MasterKey.alg.SCRYPT:
       return await scrypt.deriveAsync(passwd, salt, N, r, p, 32);
     default:
-      throw new Error('Unknown algorithm: ' + this.alg);
+      throw new Error(`Unknown algorithm: ${this.alg}.`);
   }
 };
 
diff --git a/lib/workers/jobs.js b/lib/workers/jobs.js
index 7be55d0fd..25891dcf6 100644
--- a/lib/workers/jobs.js
+++ b/lib/workers/jobs.js
@@ -60,7 +60,7 @@ jobs._execute = function execute(p) {
     case packets.types.SCRYPT:
       return jobs.scrypt(p.passwd, p.salt, p.N, p.r, p.p, p.len);
     default:
-      throw new Error('Unknown command: "' + p.cmd + '".');
+      throw new Error(`Unknown command: "${p.cmd}".`);
   }
 };
 
diff --git a/lib/workers/workerpool.js b/lib/workers/workerpool.js
index 90b157a34..60bbd9a2d 100644
--- a/lib/workers/workerpool.js
+++ b/lib/workers/workerpool.js
@@ -658,7 +658,7 @@ Worker.prototype.handlePacket = function handlePacket(packet) {
       this.emit('event', packet.items);
       break;
     case packets.types.LOG:
-      this.emit('log', 'Worker ' + this.id);
+      this.emit('log', `Worker ${this.id}.`);
       this.emit('log', packet.text);
       break;
     case packets.types.ERROR:
@@ -771,7 +771,7 @@ Worker.prototype.resolveJob = function resolveJob(id, result) {
   let job = this.pending.get(id);
 
   if (!job)
-    throw new Error('Job ' + id + ' is not in progress.');
+    throw new Error(`Job ${id} is not in progress.`);
 
   job.resolve(result);
 };
@@ -786,7 +786,7 @@ Worker.prototype.rejectJob = function rejectJob(id, err) {
   let job = this.pending.get(id);
 
   if (!job)
-    throw new Error('Job ' + id + ' is not in progress.');
+    throw new Error(`Job ${id} is not in progress.`);
 
   job.reject(err);
 };