diff --git a/lib/bcoin/coin.js b/lib/bcoin/coin.js
index 217c4397..584011f6 100644
--- a/lib/bcoin/coin.js
+++ b/lib/bcoin/coin.js
@@ -45,7 +45,9 @@ function Coin(tx, index) {
     this.version = tx.version;
     this.height = tx.height;
     this.value = tx.outputs[index].value;
-    this.script = tx.outputs[index].script;
+    if (tx.mutable)
+      this.value = this.value.clone();
+    this.script = bcoin.script(tx.outputs[index].script, false);
     this.coinbase = tx.isCoinbase();
     this.hash = tx.hash('hex');
     this.index = index;
@@ -55,7 +57,7 @@ function Coin(tx, index) {
     this.version = options.version;
     this.height = options.height;
     this.value = options.value;
-    this.script = bcoin.script(options.script);
+    this.script = bcoin.script(options.script, false);
     this.coinbase = options.coinbase;
     this.hash = options.hash;
     this.index = options.index;
diff --git a/lib/bcoin/mempool.js b/lib/bcoin/mempool.js
index a8fe922d..917bcc3d 100644
--- a/lib/bcoin/mempool.js
+++ b/lib/bcoin/mempool.js
@@ -478,6 +478,9 @@ Mempool.prototype.addTX = function addTX(tx, callback, force) {
   if (!unlock)
     return;
 
+  if (tx.mutable)
+    tx = tx.toTX();
+
   if (this.chain.segwitActive) {
     flags |= constants.flags.VERIFY_WITNESS;
     flags |= constants.flags.VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM;
diff --git a/lib/bcoin/miner.js b/lib/bcoin/miner.js
index 8936a428..10971438 100644
--- a/lib/bcoin/miner.js
+++ b/lib/bcoin/miner.js
@@ -441,7 +441,12 @@ MinerBlock.prototype.updateMerkle = function updateMerkle() {
  */
 
 MinerBlock.prototype.addTX = function addTX(tx) {
-  var size = this.block.getVirtualSize(true) + tx.getVirtualSize();
+  var size;
+
+  if (tx.mutable)
+    tx = tx.toTX();
+
+  size = this.block.getVirtualSize(true) + tx.getVirtualSize();
 
   // Deliver me from the block size debate, please
   if (size > constants.block.MAX_SIZE)
@@ -574,6 +579,8 @@ MinerBlock.prototype.mine = function mine(callback) {
     if (!self.findNonce())
       return self.mine(callback);
 
+    self.block.txs[0] = self.block.txs[0].toTX();
+
     return callback(null, self.block);
   }, 100);
 };
@@ -585,6 +592,7 @@ MinerBlock.prototype.mine = function mine(callback) {
 
 MinerBlock.prototype.mineSync = function mineSync() {
   while (!this.findNonce());
+  this.block.txs[0] = this.block.txs[0].toTX();
   return this.block;
 };
 
diff --git a/lib/bcoin/mtx.js b/lib/bcoin/mtx.js
index 30893e70..e3fd9b76 100644
--- a/lib/bcoin/mtx.js
+++ b/lib/bcoin/mtx.js
@@ -75,6 +75,7 @@ function MTX(options) {
   this.ps = options.ps != null ? options.ps : utils.now();
   this.changeIndex = options.changeIndex != null ? options.changeIndex : -1;
   this.height = -1;
+  this.mutable = true;
 
   this._hash = null;
   this._whash = null;
@@ -254,12 +255,6 @@ MTX.prototype.addInput = function addInput(options, index) {
 
   input = bcoin.input(options, true);
 
-  if (options.script instanceof Script)
-    input.script = options.script.clone();
-
-  if (options.witness instanceof Witness)
-    input.witness = options.witness.clone();
-
   this.inputs.push(input);
 
   return this;
@@ -828,9 +823,7 @@ MTX.prototype.scriptOutput = function scriptOutput(index, options) {
   output = this.outputs[index];
   assert(output);
 
-  if (options.script instanceof Script)
-    output.script = options.script.clone();
-  else if (options.script)
+  if (options.script)
     output.script = Script(options.script);
   else
     output.script = Script.createOutputScript(options);
diff --git a/lib/bcoin/output.js b/lib/bcoin/output.js
index 6029082a..44cf1417 100644
--- a/lib/bcoin/output.js
+++ b/lib/bcoin/output.js
@@ -39,7 +39,7 @@ function Output(options, mutable) {
 
   this.mutable = !!mutable;
   this.value = utils.satoshi(value || new bn(0));
-  this.script = bcoin.script(options.script, this.mutable);
+  this.script = bcoin.script(options.script, false);
 
   assert(typeof value !== 'number');
   assert(!this.mutable || !this.value.isNeg());
diff --git a/lib/bcoin/peer.js b/lib/bcoin/peer.js
index f4c885ae..b9577982 100644
--- a/lib/bcoin/peer.js
+++ b/lib/bcoin/peer.js
@@ -312,10 +312,14 @@ Peer.prototype.broadcast = function broadcast(items) {
     items = [items];
 
   items.forEach(function(item) {
-    var key = item.hash('hex');
-    var old = this._broadcast.map[key];
-    var type = item.type;
-    var entry, packetType;
+    var key, old, type, entry, packetType;
+
+    if (item.mutable)
+      item = item.toTX();
+
+    key = item.hash('hex');
+    old = this._broadcast.map[key];
+    type = item.type;
 
     if (typeof type === 'string')
       type = constants.inv[type.toUpperCase()];
diff --git a/lib/bcoin/pool.js b/lib/bcoin/pool.js
index d2c57c6d..bc30afb2 100644
--- a/lib/bcoin/pool.js
+++ b/lib/bcoin/pool.js
@@ -1866,10 +1866,14 @@ Pool.prototype.sendTX = function sendTX(tx, callback) {
 Pool.prototype.broadcast = function broadcast(msg, callback) {
   var self = this;
   var e = new EventEmitter();
+  var entry;
 
   callback = utils.once(callback);
 
-  var entry = {
+  if (msg.mutable)
+    msg = msg.toTX();
+
+  entry = {
     msg: msg,
     e: e,
     timer: setTimeout(function() {
diff --git a/lib/bcoin/script.js b/lib/bcoin/script.js
index 8b5a6f26..8d0cc901 100644
--- a/lib/bcoin/script.js
+++ b/lib/bcoin/script.js
@@ -44,8 +44,8 @@ var STACK_NEGATE = new Buffer([0xff]);
 
 function Witness(items, mutable) {
   if (items instanceof Witness) {
-    items.mutable = !!mutable;
-    items.redeem = null;
+    if (mutable || items.mutable)
+      return items.clone(mutable);
     return items;
   }
 
@@ -82,8 +82,8 @@ Witness.prototype.inspect = function inspect() {
  * @returns {Witness} A clone of the current witness object.
  */
 
-Witness.prototype.clone = function clone() {
-  return new Witness(this.items.slice());
+Witness.prototype.clone = function clone(mutable) {
+  return new Witness(this.items.slice(), mutable);
 };
 
 /**
@@ -794,9 +794,8 @@ Stack.isStack = function isStack(obj) {
 
 function Script(code, mutable) {
   if (code instanceof Script) {
-    code.mutable = !!mutable;
-    code.raw = null;
-    code.redeem = null;
+    if (mutable || code.mutable)
+      return code.clone(mutable);
     return code;
   }
 
@@ -834,8 +833,8 @@ function Script(code, mutable) {
  * @returns {Script} Cloned script.
  */
 
-Script.prototype.clone = function clone() {
-  return new Script(this.code.slice());
+Script.prototype.clone = function clone(mutable) {
+  return new Script(this.code.slice(), mutable);
 };
 
 /**
diff --git a/lib/bcoin/txdb.js b/lib/bcoin/txdb.js
index 0a621414..fd023a9c 100644
--- a/lib/bcoin/txdb.js
+++ b/lib/bcoin/txdb.js
@@ -337,6 +337,9 @@ TXDB.prototype._add = function add(tx, map, callback, force) {
 
   callback = utils.wrap(callback, unlock);
 
+  if (tx.mutable)
+    tx = tx.toTX();
+
   // Attempt to confirm tx before adding it.
   this._confirm(tx, map, function(err, existing) {
     if (err)