diff --git a/lib/bcoin/mempool.js b/lib/bcoin/mempool.js
index b009fd2d..1cb38434 100644
--- a/lib/bcoin/mempool.js
+++ b/lib/bcoin/mempool.js
@@ -78,7 +78,9 @@ function Mempool(options) {
   this.limitFree = this.options.limitFree !== false;
   this.limitFreeRelay = this.options.limitFreeRelay || 15;
   this.relayPriority = this.options.relayPriority !== false;
-  this.requireStandard = this.options.requireStandard !== false;
+  this.requireStandard = this.options.requireStandard != null
+    ? this.options.requireStandard
+    : network.requireStandard;
   this.rejectInsaneFees = this.options.rejectInsaneFees !== false;
 
   // Use an in-memory binary search tree by default
diff --git a/lib/bcoin/miner.js b/lib/bcoin/miner.js
index 0609a671..d6bd6512 100644
--- a/lib/bcoin/miner.js
+++ b/lib/bcoin/miner.js
@@ -146,9 +146,10 @@ Miner.prototype._init = function _init() {
 
 /**
  * Start mining.
+ * @param {Number?} version - Custom block version.
  */
 
-Miner.prototype.start = function start() {
+Miner.prototype.start = function start(version) {
   var self = this;
 
   this.stop();
@@ -156,7 +157,7 @@ Miner.prototype.start = function start() {
   this.running = true;
 
   // Create a new block and start hashing
-  this.createBlock(function(err, attempt) {
+  this.createBlock(version, function(err, attempt) {
     if (err)
       return self.emit('error', err);
 
@@ -212,19 +213,31 @@ Miner.prototype.stop = function stop() {
 
 /**
  * Create a block "attempt".
+ * @param {Number?} version - Custom block version.
  * @param {Function} callback - Returns [Error, {@link MinerBlock}].
  */
 
-Miner.prototype.createBlock = function createBlock(callback) {
+Miner.prototype.createBlock = function createBlock(version, callback) {
   var self = this;
   var ts = Math.max(bcoin.now(), this.chain.tip.ts + 1);
   var attempt;
 
+  if (typeof version === 'function') {
+    callback = version;
+    version = null;
+  }
+
+  function computeVersion(callback) {
+    if (version != null)
+      return callback(null, version);
+    self.chain.computeBlockVersion(self.chain.tip, callback);
+  }
+
   if (!this.loaded) {
     this.open(function(err) {
       if (err)
         return callback(err);
-      self.createBlock(callback);
+      self.createBlock(version, callback);
     });
     return;
   }
@@ -237,7 +250,7 @@ Miner.prototype.createBlock = function createBlock(callback) {
       return callback(err);
 
     // Calculate version with versionbits
-    self.chain.computeBlockVersion(self.chain.tip, function(err, version) {
+    computeVersion(function(err, version) {
       if (err)
         return callback(err);
 
@@ -285,14 +298,20 @@ Miner.prototype.createBlock = function createBlock(callback) {
 
 /**
  * Mine a single block.
+ * @param {Number?} version - Custom block version.
  * @param {Function} callback - Returns [Error, [{@link Block}]].
  */
 
-Miner.prototype.mineBlock = function mineBlock(callback) {
+Miner.prototype.mineBlock = function mineBlock(version, callback) {
   var self = this;
 
+  if (typeof version === 'function') {
+    callback = version;
+    version = null;
+  }
+
   // Create a new block and start hashing
-  this.createBlock(function(err, attempt) {
+  this.createBlock(version, function(err, attempt) {
     if (err)
       return callback(err);
 
diff --git a/lib/bcoin/protocol/network.js b/lib/bcoin/protocol/network.js
index dc1b5261..cc29957c 100644
--- a/lib/bcoin/protocol/network.js
+++ b/lib/bcoin/protocol/network.js
@@ -401,6 +401,15 @@ main.address.prefixesByVal = utils.revMap(main.address.prefixes);
 
 main.address.versionsByVal = utils.revMap(main.address.versions);
 
+/**
+ * Default value for whether the mempool
+ * accepts non-standard transactions.
+ * @const {Boolean}
+ * @default
+ */
+
+main.requireStandard = true;
+
 /*
  * Testnet (v3)
  * https://en.bitcoin.it/wiki/Testnet
@@ -534,6 +543,8 @@ testnet.address = {
 testnet.address.prefixesByVal = utils.revMap(testnet.address.prefixes);
 testnet.address.versionsByVal = utils.revMap(testnet.address.versions);
 
+testnet.requireStandard = false;
+
 /*
  * Regtest
  */
@@ -659,6 +670,8 @@ regtest.address = {
 regtest.address.prefixesByVal = utils.revMap(regtest.address.prefixes);
 regtest.address.versionsByVal = utils.revMap(regtest.address.versions);
 
+regtest.requireStandard = false;
+
 /*
  * segnet3
  */
@@ -767,6 +780,8 @@ segnet3.address = {
 segnet3.address.prefixesByVal = utils.revMap(segnet3.address.prefixes);
 segnet3.address.versionsByVal = utils.revMap(segnet3.address.versions);
 
+segnet3.requireStandard = false;
+
 /*
  * segnet4
  */
@@ -888,3 +903,5 @@ segnet4.address = {
 
 segnet4.address.prefixesByVal = utils.revMap(segnet4.address.prefixes);
 segnet4.address.versionsByVal = utils.revMap(segnet4.address.versions);
+
+segnet4.requireStandard = false;