diff --git a/lib/http/rpc.js b/lib/http/rpc.js
index a7017535..5bfa21ff 100644
--- a/lib/http/rpc.js
+++ b/lib/http/rpc.js
@@ -791,7 +791,7 @@ RPC.prototype._txToJSON = function _txToJSON(tx, entry) {
       if (tx.isCoinbase()) {
         out.coinbase = input.script.toJSON();
       } else {
-        out.txid = input.prevout.rhash();
+        out.txid = input.prevout.txid();
         out.vout = input.prevout.index;
         out.scriptSig = {
           asm: input.script.toASM(),
@@ -3381,7 +3381,7 @@ RPC.prototype.listlockunspent = co(function* listlockunspent(args) {
   for (i = 0; i < outpoints.length; i++) {
     outpoint = outpoints[i];
     out.push({
-      txid: outpoint.rhash(),
+      txid: outpoint.txid(),
       vout: outpoint.index
     });
   }
@@ -3749,7 +3749,7 @@ RPC.prototype.listunspent = co(function* listunspent(args) {
     ring = yield wallet.getKey(hash);
 
     out.push({
-      txid: coin.rhash(),
+      txid: coin.txid(),
       vout: coin.index,
       address: address ? address.toBase58(this.network) : null,
       account: ring ? ring.name : undefined,
diff --git a/lib/primitives/coin.js b/lib/primitives/coin.js
index fb8635f2..14fe812d 100644
--- a/lib/primitives/coin.js
+++ b/lib/primitives/coin.js
@@ -62,17 +62,21 @@ Coin.prototype.fromOptions = function fromOptions(options) {
   assert(options, 'Coin data is required.');
 
   if (options.version != null) {
-    assert(util.isUInt32(options.version));
+    assert(util.isUInt32(options.version), 'Version must be a uint32.');
     this.version = options.version;
   }
 
   if (options.height != null) {
-    assert(options.height === -1 || util.isUInt32(options.height));
-    this.height = options.height;
+    if (options.height !== -1) {
+      assert(util.isUInt32(options.height), 'Height must be a uint32.');
+      this.height = options.height;
+    } else {
+      this.height = -1;
+    }
   }
 
   if (options.value != null) {
-    assert(util.isUInt53(options.value));
+    assert(util.isUInt53(options.value), 'Value must be a uint53.');
     this.value = options.value;
   }
 
@@ -80,17 +84,18 @@ Coin.prototype.fromOptions = function fromOptions(options) {
     this.script.fromOptions(options.script);
 
   if (options.coinbase != null) {
-    assert(typeof options.coinbase === 'boolean');
+    assert(typeof options.coinbase === 'boolean',
+      'Coinbase must be a boolean.');
     this.coinbase = options.coinbase;
   }
 
   if (options.hash != null) {
-    assert(typeof options.hash === 'string');
+    assert(typeof options.hash === 'string', 'Hash must be a string.');
     this.hash = options.hash;
   }
 
   if (options.index != null) {
-    assert(util.isUInt32(options.index));
+    assert(util.isUInt32(options.index), 'Index must be a uint32.');
     this.index = options.index;
   }
 
@@ -107,6 +112,16 @@ Coin.fromOptions = function fromOptions(options) {
   return new Coin().fromOptions(options);
 };
 
+/**
+ * Clone the coin.
+ * @private
+ * @returns {Coin}
+ */
+
+Coin.prototype.clone = function clone() {
+  assert(false, 'Coins are not cloneable.');
+};
+
 /**
  * Calculate number of confirmations since coin was created.
  * @param {Number?} height - Current chain height. Network
@@ -172,6 +187,15 @@ Coin.prototype.rhash = function rhash() {
   return util.revHex(this.hash);
 };
 
+/**
+ * Get little-endian hash.
+ * @returns {Hash}
+ */
+
+Coin.prototype.txid = function txid() {
+  return this.rhash();
+};
+
 /**
  * Convert the coin to a more user-friendly object.
  * @returns {Object}
@@ -239,20 +263,25 @@ Coin.prototype.getJSON = function getJSON(network, minimal) {
 
 Coin.prototype.fromJSON = function fromJSON(json) {
   assert(json, 'Coin data required.');
-  assert(util.isNumber(json.version));
-  assert(util.isNumber(json.height));
-  assert(typeof json.value === 'string');
-  assert(typeof json.coinbase === 'boolean');
-  assert(!json.hash || typeof json.hash === 'string');
-  assert(!json.index || util.isNumber(json.index));
+  assert(util.isUInt32(json.version), 'Version must be a uint32.');
+  assert(json.height === -1 || util.isUInt32(json.height),
+    'Height must be a uint32.');
+  assert(typeof json.value === 'string', 'Value must be a string.');
+  assert(typeof json.coinbase === 'boolean', 'Coinbase must be a boolean.');
 
   this.version = json.version;
   this.height = json.height;
   this.value = Amount.value(json.value);
   this.script.fromJSON(json.script);
   this.coinbase = json.coinbase;
-  this.hash = json.hash ? util.revHex(json.hash) : encoding.NULL_HASH;
-  this.index = json.index != null ? json.index : 0;
+
+  if (json.hash != null) {
+    assert(typeof json.hash === 'string', 'Hash must be a string.');
+    assert(json.hash.length === 64, 'Hash must be a string.');
+    assert(util.isUInt32(json.index), 'Index must be a uint32.');
+    this.hash = util.revHex(json.hash);
+    this.index = json.index;
+  }
 
   return this;
 };
@@ -365,9 +394,9 @@ Coin.fromRaw = function fromRaw(data, enc) {
  */
 
 Coin.prototype.fromTX = function fromTX(tx, index, height) {
-  assert(util.isNumber(index));
-  assert(index < tx.outputs.length);
+  assert(typeof index === 'number');
   assert(typeof height === 'number');
+  assert(index >= 0 && index < tx.outputs.length);
   this.version = tx.version;
   this.height = height;
   this.value = tx.outputs[index].value;
diff --git a/lib/primitives/input.js b/lib/primitives/input.js
index 4705f10a..4a334b8d 100644
--- a/lib/primitives/input.js
+++ b/lib/primitives/input.js
@@ -48,7 +48,6 @@ function Input(options) {
 
 Input.prototype.fromOptions = function fromOptions(options) {
   assert(options, 'Input data is required.');
-  assert(options.prevout);
 
   this.prevout.fromOptions(options.prevout);
 
@@ -56,7 +55,7 @@ Input.prototype.fromOptions = function fromOptions(options) {
     this.script.fromOptions(options.script);
 
   if (options.sequence != null) {
-    assert(util.isUInt32(options.sequence));
+    assert(util.isUInt32(options.sequence), 'Sequence must be a uint32.');
     this.sequence = options.sequence;
   }
 
@@ -76,6 +75,20 @@ Input.fromOptions = function fromOptions(options) {
   return new Input().fromOptions(options);
 };
 
+/**
+ * Clone the input.
+ * @returns {Input}
+ */
+
+Input.prototype.clone = function clone() {
+  var input = new Input();
+  input.prevout = this.prevout;
+  input.script.inject(this.script);
+  input.sequence = this.sequence;
+  input.witness.inject(this.witness);
+  return input;
+};
+
 /**
  * Get the previous output script type as a string.
  * Will "guess" based on the input script and/or
@@ -300,7 +313,7 @@ Input.prototype.getJSON = function getJSON(network, coin) {
 
 Input.prototype.fromJSON = function fromJSON(json) {
   assert(json, 'Input data is required.');
-  assert(util.isUInt32(json.sequence));
+  assert(util.isUInt32(json.sequence), 'Sequence must be a uint32.');
   this.prevout.fromJSON(json.prevout);
   this.script.fromJSON(json.script);
   this.witness.fromJSON(json.witness);
@@ -453,7 +466,7 @@ Input.fromCoin = function fromCoin(coin) {
 Input.prototype.fromTX = function fromTX(tx, index) {
   assert(tx);
   assert(typeof index === 'number');
-  assert(index < tx.outputs.length);
+  assert(index >= 0 && index < tx.outputs.length);
   this.prevout.hash = tx.hash('hex');
   this.prevout.index = index;
   return this;
diff --git a/lib/primitives/mtx.js b/lib/primitives/mtx.js
index aeb1e356..f8a1c6da 100644
--- a/lib/primitives/mtx.js
+++ b/lib/primitives/mtx.js
@@ -70,35 +70,40 @@ MTX.prototype.fromOptions = function fromOptions(options) {
   var i;
 
   if (options.version != null) {
-    assert(util.isUInt32(options.version));
+    assert(util.isUInt32(options.version), 'Version must a be uint32.');
     this.version = options.version;
   }
 
   if (options.flag != null) {
-    assert(util.isUInt8(options.flag));
+    assert(util.isUInt8(options.flag), 'Flag must be a uint8.');
     this.flag = options.flag;
   }
 
   if (options.inputs) {
-    assert(Array.isArray(options.inputs));
+    assert(Array.isArray(options.inputs), 'Inputs must be an array.');
     for (i = 0; i < options.inputs.length; i++)
       this.addInput(options.inputs[i]);
   }
 
   if (options.outputs) {
-    assert(Array.isArray(options.outputs));
+    assert(Array.isArray(options.outputs), 'Outputs must be an array.');
     for (i = 0; i < options.outputs.length; i++)
       this.addOutput(options.outputs[i]);
   }
 
   if (options.locktime != null) {
-    assert(util.isUInt32(options.locktime));
+    assert(util.isUInt32(options.locktime), 'Locktime must be a uint32.');
     this.locktime = options.locktime;
   }
 
   if (options.changeIndex != null) {
-    assert(util.isNumber(options.changeIndex));
-    this.changeIndex = options.changeIndex;
+    if (options.changeIndex !== -1) {
+      assert(util.isUInt32(options.changeIndex),
+        'Change index must be a uint32.');
+      this.changeIndex = options.changeIndex;
+    } else {
+      this.changeIndex = -1;
+    }
   }
 
   return this;
@@ -115,12 +120,16 @@ MTX.fromOptions = function fromOptions(options) {
 };
 
 /**
- * Clone the transaction.
+ * Clone the transaction. Note that
+ * this will not carry over the view.
  * @returns {MTX}
  */
 
 MTX.prototype.clone = function clone() {
-  return new MTX(this);
+  var mtx = new MTX();
+  mtx.inject(this);
+  mtx.changeIndex = this.changeIndex;
+  return mtx;
 };
 
 /**
@@ -211,8 +220,8 @@ MTX.prototype.addTX = function addTX(tx, index, height) {
 
 /**
  * Add an output.
- * @param {Address|Script|Output|Object} options
- * @param {Amount?} value - Only needs to be present for non-output options.
+ * @param {Address|Script|Output|Object} script - Script or output options.
+ * @param {Amount?} value
  * @returns {Output}
  *
  * @example
@@ -222,24 +231,14 @@ MTX.prototype.addTX = function addTX(tx, index, height) {
  * mtx.addOutput(script, 100000);
  */
 
-MTX.prototype.addOutput = function addOutput(options, value) {
+MTX.prototype.addOutput = function addOutput(script, value) {
   var output;
 
-  if (typeof options === 'string')
-    options = Address.fromBase58(options);
-
-  if (options instanceof Address)
-    options = Script.fromAddress(options);
-
-  output = new Output();
-
-  if (options instanceof Script) {
+  if (value != null) {
     assert(util.isUInt53(value), 'Value must be a uint53.');
-    output.script.fromOptions(options);
-    output.value = value;
+    output = Output.fromScript(script, value);
   } else {
-    output.fromOptions(options);
-    assert(util.isUInt53(output.value), 'Value must be a uint53.');
+    output = Output.fromOptions(script);
   }
 
   this.outputs.push(output);
@@ -1404,7 +1403,7 @@ MTX.fromRaw = function fromRaw(data, enc) {
  */
 
 MTX.prototype.toTX = function toTX() {
-  return new TX(this);
+  return new TX().inject(this);
 };
 
 /**
@@ -1414,7 +1413,7 @@ MTX.prototype.toTX = function toTX() {
  */
 
 MTX.fromTX = function fromTX(tx) {
-  return new MTX(tx);
+  return new MTX().inject(tx);
 };
 
 /**
@@ -1834,8 +1833,8 @@ function sortRandom(a, b) {
 }
 
 function sortInputs(a, b) {
-  var ahash = a.prevout.rhash();
-  var bhash = b.prevout.rhash();
+  var ahash = a.prevout.txid();
+  var bhash = b.prevout.txid();
   var cmp = util.strcmp(ahash, bhash);
 
   if (cmp !== 0)
diff --git a/lib/primitives/outpoint.js b/lib/primitives/outpoint.js
index 17959f4b..db07be5e 100644
--- a/lib/primitives/outpoint.js
+++ b/lib/primitives/outpoint.js
@@ -26,8 +26,15 @@ function Outpoint(hash, index) {
   if (!(this instanceof Outpoint))
     return new Outpoint(hash, index);
 
-  this.hash = hash || encoding.NULL_HASH;
-  this.index = index != null ? index : 0xffffffff;
+  this.hash = encoding.NULL_HASH;
+  this.index = 0xffffffff;
+
+  if (hash != null) {
+    assert(typeof hash === 'string', 'Hash must be a string.');
+    assert(util.isUInt32(index), 'Index must be a uint32.');
+    this.hash = hash;
+    this.index = index;
+  }
 }
 
 /**
@@ -37,8 +44,9 @@ function Outpoint(hash, index) {
  */
 
 Outpoint.prototype.fromOptions = function fromOptions(options) {
-  assert(typeof options.hash === 'string');
-  assert(util.isNumber(options.index));
+  assert(options, 'Outpoint data is required.');
+  assert(typeof options.hash === 'string', 'Hash must be a string.');
+  assert(util.isUInt32(options.index), 'Index must be a uint32.');
   this.hash = options.hash;
   this.index = options.index;
   return this;
@@ -73,6 +81,15 @@ Outpoint.prototype.rhash = function rhash() {
   return util.revHex(this.hash);
 };
 
+/**
+ * Get little-endian hash.
+ * @returns {Hash}
+ */
+
+Outpoint.prototype.txid = function txid() {
+  return this.rhash();
+};
+
 /**
  * Serialize outpoint to a key
  * suitable for a hash table.
@@ -185,8 +202,9 @@ Outpoint.fromRaw = function fromRaw(data) {
  */
 
 Outpoint.prototype.fromJSON = function fromJSON(json) {
-  assert(typeof json.hash === 'string');
-  assert(util.isNumber(json.index));
+  assert(json, 'Outpoint data is required.');
+  assert(typeof json.hash === 'string', 'Hash must be a string.');
+  assert(util.isUInt32(json.index), 'Index must be a uint32.');
   this.hash = util.revHex(json.hash);
   this.index = json.index;
   return this;
@@ -225,7 +243,8 @@ Outpoint.fromJSON = function fromJSON(json) {
  */
 
 Outpoint.prototype.fromTX = function fromTX(tx, index) {
-  assert(util.isNumber(index));
+  assert(tx);
+  assert(typeof index === 'number');
   this.hash = tx.hash('hex');
   this.index = index;
   return this;
diff --git a/lib/primitives/output.js b/lib/primitives/output.js
index 76e2cf4c..d8bb11a8 100644
--- a/lib/primitives/output.js
+++ b/lib/primitives/output.js
@@ -11,6 +11,7 @@ var assert = require('assert');
 var util = require('../utils/util');
 var Amount = require('../btc/amount');
 var Network = require('../protocol/network');
+var Address = require('../primitives/address');
 var Script = require('../script/script');
 var StaticWriter = require('../utils/staticwriter');
 var BufferReader = require('../utils/reader');
@@ -47,7 +48,7 @@ Output.prototype.fromOptions = function fromOptions(options) {
   assert(options, 'Output data is required.');
 
   if (options.value) {
-    assert(util.isInt53(options.value));
+    assert(util.isUInt53(options.value), 'Value must be a uint53.');
     this.value = options.value;
   }
 
@@ -70,6 +71,53 @@ Output.fromOptions = function fromOptions(options) {
   return new Output().fromOptions(options);
 };
 
+/**
+ * Inject properties from script/value pair.
+ * @private
+ * @param {Script|Address} script
+ * @param {Amount} value
+ * @returns {Output}
+ */
+
+Output.prototype.fromScript = function fromScript(script, value) {
+  if (typeof script === 'string')
+    script = Address.fromBase58(script);
+
+  if (script instanceof Address)
+    script = Script.fromAddress(script);
+
+  assert(script instanceof Script, 'Script must be a Script.');
+  assert(util.isUInt53(value), 'Value must be a uint53.');
+
+  this.script = script;
+  this.value = value;
+
+  return this;
+};
+
+/**
+ * Instantiate output from script/value pair.
+ * @param {Script|Address} script
+ * @param {Amount} value
+ * @returns {Output}
+ */
+
+Output.fromScript = function fromScript(script, value) {
+  return new Output().fromScript(script, value);
+};
+
+/**
+ * Clone the output.
+ * @returns {Output}
+ */
+
+Output.prototype.clone = function clone() {
+  var output = new Output();
+  output.value = this.value;
+  output.script.inject(this.script);
+  return output;
+};
+
 /**
  * Get the script type as a string.
  * @returns {ScriptType} type
@@ -199,7 +247,8 @@ Output.prototype.isDust = function isDust(rate) {
  */
 
 Output.prototype.fromJSON = function fromJSON(json) {
-  assert(typeof json.value === 'string');
+  assert(json, 'Output data is required.');
+  assert(typeof json.value === 'string', 'Value must be a string.');
   this.value = Amount.value(json.value);
   this.script.fromJSON(json.script);
   return this;
diff --git a/lib/primitives/tx.js b/lib/primitives/tx.js
index dd874d5b..07a4e1ca 100644
--- a/lib/primitives/tx.js
+++ b/lib/primitives/tx.js
@@ -94,29 +94,29 @@ TX.prototype.fromOptions = function fromOptions(options) {
   assert(options, 'TX data is required.');
 
   if (options.version != null) {
-    assert(util.isUInt32(options.version));
+    assert(util.isUInt32(options.version), 'Version must be a uint32.');
     this.version = options.version;
   }
 
   if (options.flag != null) {
-    assert(util.isUInt8(options.flag));
+    assert(util.isUInt8(options.flag), 'Flag must be a uint8.');
     this.flag = options.flag;
   }
 
   if (options.inputs) {
-    assert(Array.isArray(options.inputs));
+    assert(Array.isArray(options.inputs), 'Inputs must be an array.');
     for (i = 0; i < options.inputs.length; i++)
       this.inputs.push(new Input(options.inputs[i]));
   }
 
   if (options.outputs) {
-    assert(Array.isArray(options.outputs));
+    assert(Array.isArray(options.outputs), 'Outputs must be an array.');
     for (i = 0; i < options.outputs.length; i++)
       this.outputs.push(new Output(options.outputs[i]));
   }
 
   if (options.locktime != null) {
-    assert(util.isUInt32(options.locktime));
+    assert(util.isUInt32(options.locktime), 'Locktime must be a uint32.');
     this.locktime = options.locktime;
   }
 
@@ -139,7 +139,36 @@ TX.fromOptions = function fromOptions(options) {
  */
 
 TX.prototype.clone = function clone() {
-  return new TX(this);
+  return new TX().inject(this);
+};
+
+/**
+ * Inject properties from tx.
+ * Used for cloning.
+ * @private
+ * @param {TX} tx
+ * @returns {TX}
+ */
+
+TX.prototype.inject = function inject(tx) {
+  var i, input, output;
+
+  this.version = tx.version;
+  this.flag = tx.flag;
+
+  for (i = 0; i < tx.inputs.length; i++) {
+    input = tx.inputs[i];
+    this.inputs.push(input.clone());
+  }
+
+  for (i = 0; i < tx.outputs.length; i++) {
+    output = tx.outputs[i];
+    this.outputs.push(output.clone());
+  }
+
+  this.locktime = tx.locktime;
+
+  return this;
 };
 
 /**
diff --git a/lib/script/script.js b/lib/script/script.js
index 96f83c68..369d5da4 100644
--- a/lib/script/script.js
+++ b/lib/script/script.js
@@ -147,14 +147,14 @@ Script.prototype.fromOptions = function fromOptions(options) {
   if (options.raw) {
     if (!options.code)
       return this.fromRaw(options.raw);
-    assert(Buffer.isBuffer(options.raw));
+    assert(Buffer.isBuffer(options.raw), 'Raw must be a Buffer.');
     this.raw = options.raw;
   }
 
   if (options.code) {
     if (!options.raw)
       return this.fromCode(options.code);
-    assert(Array.isArray(options.code));
+    assert(Array.isArray(options.code), 'Code must be an array.');
     this.code = options.code;
   }
 
@@ -284,7 +284,21 @@ Script.fromCode = function fromCode(code) {
  */
 
 Script.prototype.clone = function clone() {
-  return new Script(this.raw);
+  return new Script().inject(this);
+};
+
+/**
+ * Inject properties from script.
+ * Used for cloning.
+ * @private
+ * @param {Script} script
+ * @returns {Script}
+ */
+
+Script.prototype.inject = function inject(script) {
+  this.code = script.code.slice();
+  this.raw = script.raw;
+  return this;
 };
 
 /**
@@ -388,7 +402,7 @@ Script.prototype.toJSON = function toJSON() {
  */
 
 Script.prototype.fromJSON = function fromJSON(json) {
-  assert(typeof json === 'string');
+  assert(typeof json === 'string', 'Code must be a string.');
   return this.fromRaw(new Buffer(json, 'hex'));
 };
 
@@ -417,12 +431,14 @@ Script.prototype.getSubscript = function getSubscript(lastSep) {
 
   for (i = lastSep; i < this.code.length; i++) {
     op = this.code[i];
+
     if (op.value === -1)
       break;
+
     code.push(op);
   }
 
-  return new Script(code);
+  return Script.fromCode(code);
 };
 
 /**
@@ -434,21 +450,42 @@ Script.prototype.getSubscript = function getSubscript(lastSep) {
  */
 
 Script.prototype.removeSeparators = function removeSeparators() {
-  var code = [];
-  var i, op;
+  var found = false;
+  var i, op, code;
+
+  // Optimizing for the common case:
+  // Check for any separators first.
+  for (i = 0; i < this.code.length; i++) {
+    op = this.code[i];
+
+    if (op.value === -1)
+      break;
+
+    if (op.value === opcodes.OP_CODESEPARATOR) {
+      found = true;
+      break;
+    }
+  }
+
+  if (!found)
+    return this.clone();
+
+  // Uncommon case: someone actually
+  // has a code separator. Go through
+  // and remove them all.
+  code = [];
 
   for (i = 0; i < this.code.length; i++) {
     op = this.code[i];
+
     if (op.value === -1)
       break;
+
     if (op.value !== opcodes.OP_CODESEPARATOR)
       code.push(op);
   }
 
-  if (code.length === this.code.length)
-    return this.clone();
-
-  return new Script(code);
+  return Script.fromCode(code);
 };
 
 /**
diff --git a/lib/script/witness.js b/lib/script/witness.js
index bad0fea4..1741f408 100644
--- a/lib/script/witness.js
+++ b/lib/script/witness.js
@@ -165,7 +165,20 @@ Witness.prototype.toASM = function toASM(decode) {
  */
 
 Witness.prototype.clone = function clone() {
-  return new Witness(this.items.slice());
+  return new Witness().inject(this);
+};
+
+/**
+ * Inject properties from witness.
+ * Used for cloning.
+ * @private
+ * @param {Witness} witness
+ * @returns {Witness}
+ */
+
+Witness.prototype.inject = function inject(witness) {
+  this.items = witness.items.slice();
+  return this;
 };
 
 /**
@@ -387,7 +400,7 @@ Witness.prototype.toJSON = function toJSON() {
  */
 
 Witness.prototype.fromJSON = function fromJSON(json) {
-  assert(typeof json === 'string');
+  assert(typeof json === 'string', 'Witness must be a string.');
   return this.fromRaw(new Buffer(json, 'hex'));
 };