diff --git a/lib/bcoin/chain.js b/lib/bcoin/chain.js
index d3a0fb95..7f093ff8 100644
--- a/lib/bcoin/chain.js
+++ b/lib/bcoin/chain.js
@@ -189,6 +189,11 @@ Chain.prototype.open = function open(callback) {
   this.once('open', callback);
 };
 
+Chain.prototype.close =
+Chain.prototype.destroy = function destroy(callback) {
+  this.db.close(utils.ensure(callback));
+};
+
 Chain.prototype._lock = function _lock(func, args, force) {
   return this.locker.lock(func, args, force);
 };
diff --git a/lib/bcoin/chaindb.js b/lib/bcoin/chaindb.js
index f68765f5..41bef0d1 100644
--- a/lib/bcoin/chaindb.js
+++ b/lib/bcoin/chaindb.js
@@ -174,7 +174,8 @@ ChainDB.prototype.open = function open(callback) {
   this.once('open', callback);
 };
 
-ChainDB.prototype.close = function close(callback) {
+ChainDB.prototype.close =
+ChainDB.prototype.destroy = function destroy(callback) {
   callback = utils.ensure(callback);
   this.db.close(callback);
 };
diff --git a/lib/bcoin/fullnode.js b/lib/bcoin/fullnode.js
index 9ad12c96..24cfe658 100644
--- a/lib/bcoin/fullnode.js
+++ b/lib/bcoin/fullnode.js
@@ -193,6 +193,17 @@ Fullnode.prototype.open = function open(callback) {
   this.once('open', callback);
 };
 
+Fullnode.prototype.close =
+Fullnode.prototype.destroy = function destroy(callback) {
+  utils.parallel([
+    this.pool.close.bind(this.pool),
+    this.http.close.bind(this.http),
+    this.mempool.close.bind(this.mempool),
+    this.walletdb.close.bind(this.walletdb),
+    this.chain.close.bind(this.chain)
+  ], callback);
+};
+
 Fullnode.prototype.createWallet = function createWallet(options, callback) {
   var self = this;
   callback = utils.ensure(callback);
diff --git a/lib/bcoin/http/http.js b/lib/bcoin/http/http.js
index 44227ad1..31cb93cd 100644
--- a/lib/bcoin/http/http.js
+++ b/lib/bcoin/http/http.js
@@ -245,6 +245,10 @@ HTTPServer.prototype.listen = function listen(port, host, callback) {
   });
 };
 
+HTTPServer.prototype.close = function close(callback) {
+  this.server.close(callback);
+};
+
 /**
  * Helpers
  */
diff --git a/lib/bcoin/http/server.js b/lib/bcoin/http/server.js
index fb5a18f9..82f00f21 100644
--- a/lib/bcoin/http/server.js
+++ b/lib/bcoin/http/server.js
@@ -421,6 +421,11 @@ NodeServer.prototype.open = function open(callback) {
   this.once('open', callback);
 };
 
+NodeServer.prototype.close =
+NodeServer.prototype.destroy = function destroy(callback) {
+  this.server.close(callback);
+};
+
 NodeServer.prototype._initIO = function _initIO() {
   var self = this;
 
diff --git a/lib/bcoin/mempool.js b/lib/bcoin/mempool.js
index 5ca8c14e..7bb041cf 100644
--- a/lib/bcoin/mempool.js
+++ b/lib/bcoin/mempool.js
@@ -127,6 +127,11 @@ Mempool.prototype.open = function open(callback) {
   return this.once('open', callback);
 };
 
+Mempool.prototype.close =
+Mempool.prototype.destroy = function destroy(callback) {
+  this.db.close(utils.ensure(callback));
+};
+
 Mempool.prototype.addBlock = function addBlock(block, callback, force) {
   var self = this;
   var unlock = this._lock(addBlock, [block, callback], force);
diff --git a/lib/bcoin/mtx.js b/lib/bcoin/mtx.js
index 962d3481..396000fb 100644
--- a/lib/bcoin/mtx.js
+++ b/lib/bcoin/mtx.js
@@ -649,9 +649,6 @@ MTX.prototype.addOutput = function addOutput(obj, value) {
 
   this.outputs.push(output);
 
-  if (options.script)
-    output.script = options.script.clone();
-
   this.scriptOutput(this.outputs.length - 1, options);
 
   return this;
@@ -670,7 +667,7 @@ MTX.prototype.scriptOutput = function scriptOutput(index, options) {
   assert(output);
 
   if (options.script)
-    output.script = options.script;
+    output.script = options.script.clone();
   else
     output.script = Script.createOutputScript(options);
 };
@@ -955,7 +952,7 @@ MTX.prototype.fill = function fill(coins, options) {
   }
 
   assert(coins);
-  assert(options.changeAddress);
+  assert(options.changeAddress, '`changeAddress` is required.');
 
   result = this.selectCoins(coins, options);
 
diff --git a/lib/bcoin/pool.js b/lib/bcoin/pool.js
index f2348b73..d066d83c 100644
--- a/lib/bcoin/pool.js
+++ b/lib/bcoin/pool.js
@@ -295,17 +295,19 @@ Pool.prototype.getHeaders = function getHeaders(peer, top, stop, callback) {
   });
 };
 
-Pool.prototype.startServer = function startServer() {
+Pool.prototype.startServer = function startServer(callback) {
   var self = this;
   var net;
 
+  callback = utils.ensure(callback);
+
   if (bcoin.isBrowser)
-    return;
+    return utils.nextTick(callback);
 
   net = require('n' + 'et');
 
   if (!this.options.listen)
-    return;
+    return utils.nextTick(callback);
 
   assert(!this.server);
 
@@ -322,17 +324,19 @@ Pool.prototype.startServer = function startServer() {
       data.address, data.port);
   });
 
-  this.server.listen(network.port, '0.0.0.0');
+  this.server.listen(network.port, '0.0.0.0', callback);
 };
 
-Pool.prototype.stopServer = function stopServer() {
+Pool.prototype.stopServer = function stopServer(callback) {
+  callback = utils.ensure(callback);
+
   if (bcoin.isBrowser)
-    return;
+    return utils.nextTick(callback);
 
   if (!this.server)
-    return;
+    return utils.nextTick(callback);
 
-  this.server.close();
+  this.server.close(callback);
   delete this.server;
 };
 
@@ -1706,29 +1710,42 @@ Pool.prototype.broadcast = function broadcast(msg, callback) {
   return e;
 };
 
-Pool.prototype.destroy = function destroy() {
+Pool.prototype.close =
+Pool.prototype.destroy = function destroy(callback) {
+  callback = utils.ensure(callback);
+
   if (this.destroyed)
-    return;
+    return utils.nextTick(callback);
 
   this.destroyed = true;
 
-  if (this.peers.load)
-    this.peers.load.destroy();
+  this.stopSync();
 
   this.inv.list.forEach(function(entry) {
     clearTimeout(entry.timer);
     entry.timer = null;
   });
 
-  this.peers.pending.slice().forEach(function(peer) {
-    peer.destroy();
-  });
+  Object.keys(this.request.map).forEach(function(hash) {
+    this.request.map[hash].finish();
+  }, this);
+
+  if (this.peers.load)
+    this.peers.load.destroy();
 
   this.peers.regular.slice().forEach(function(peer) {
     peer.destroy();
   });
 
-  this.stopServer();
+  this.peers.pending.slice().forEach(function(peer) {
+    peer.destroy();
+  });
+
+  this.peers.leeches.slice().forEach(function(peer) {
+    peer.destroy();
+  });
+
+  this.stopServer(callback);
 };
 
 Pool.prototype.getPeer = function getPeer(addr) {
diff --git a/lib/bcoin/protocol/constants.js b/lib/bcoin/protocol/constants.js
index 2869ca6b..176c500d 100644
--- a/lib/bcoin/protocol/constants.js
+++ b/lib/bcoin/protocol/constants.js
@@ -182,6 +182,8 @@ exports.opcodes = {
   OP_INVALIDOPCODE: 0xff
 };
 
+Object.freeze(exports.opcodes);
+
 exports.opcodesByVal = new Array(256);
 Object.keys(exports.opcodes).forEach(function(name) {
   var val = exports.opcodes[name];
diff --git a/lib/bcoin/script.js b/lib/bcoin/script.js
index 6250a5dd..95edb9e9 100644
--- a/lib/bcoin/script.js
+++ b/lib/bcoin/script.js
@@ -11,6 +11,9 @@ var utils = require('./utils');
 var assert = utils.assert;
 var BufferWriter = require('./writer');
 var opcodes = constants.opcodes;
+var STACK_TRUE = new Buffer([1]);
+var STACK_FALSE = new Buffer([]);
+var STACK_NEGATE = new Buffer([0xff]);
 
 function Witness(items) {
   if (!(this instanceof Witness))
@@ -103,11 +106,11 @@ Witness.fromString = function fromString(items) {
     op = items[i];
 
     if (op === '-1' || op === '1negate') {
-      op = new Buffer([0xff]);
+      op = STACK_NEGATE;
     } else if (op === '0' || op === 'false') {
-      op = new Buffer([]);
+      op = STACK_FALSE;
     } else if (op === 'true') {
-      op = new Buffer([1]);
+      op = STACK_TRUE;
     } else if (+op >= 1 && +op <= 16) {
       op = new Buffer([+op]);
     } else {
@@ -148,11 +151,11 @@ Witness.fromSymbolic = function fromSymbolic(items) {
       op = op.slice(3);
 
     if (+op === -1)
-      op = new Buffer([0xff]);
+      op = STACK_NEGATE;
     else if (+op === 0 || op === 'false')
-      op = new Buffer([]);
+      op = STACK_FALSE;
     else if (+op === 1 || op === 'true')
-      op = new Buffer([1]);
+      op = STACK_TRUE;
     else if (+op >= 1 && +op <= 16)
       op = new Buffer([+op]);
     else
@@ -573,7 +576,7 @@ Script.prototype.interpret = function interpret(stack, flags, tx, index, version
     }
 
     if (op === opcodes.OP_0) {
-      stack.push(new Buffer([]));
+      stack.push(STACK_FALSE);
       continue;
     }
 
@@ -597,7 +600,7 @@ Script.prototype.interpret = function interpret(stack, flags, tx, index, version
         break;
       }
       case opcodes.OP_1NEGATE: {
-        stack.push(new Buffer([0xff]));
+        stack.push(STACK_NEGATE);
         break;
       }
       case opcodes.OP_IF:
@@ -752,7 +755,7 @@ Script.prototype.interpret = function interpret(stack, flags, tx, index, version
             break;
           case opcodes.OP_ABS:
             if (n.cmpn(0) < 0)
-              n = n.neg();
+              n.ineg();
             break;
           case opcodes.OP_NOT:
             n = n.cmpn(0) === 0;
@@ -860,7 +863,7 @@ Script.prototype.interpret = function interpret(stack, flags, tx, index, version
             n2 = Script.num(stack.pop(), flags);
             n1 = Script.num(stack.pop(), flags);
             val = n2.cmp(n1) <= 0 && n1.cmp(n3) < 0;
-            stack.push(val.cmpn(0) !== 0 ? new Buffer([1]) : new Buffer([]));
+            stack.push(val.cmpn(0) !== 0 ? STACK_TRUE : STACK_FALSE);
             break;
         }
 
@@ -909,7 +912,7 @@ Script.prototype.interpret = function interpret(stack, flags, tx, index, version
           if (!res)
             throw new ScriptError('Equal verification failed.', op, ip);
         } else {
-          stack.push(res ? new Buffer([1]) : new Buffer([]));
+          stack.push(res ? STACK_TRUE : STACK_FALSE);
         }
         break;
       }
@@ -942,7 +945,7 @@ Script.prototype.interpret = function interpret(stack, flags, tx, index, version
           if (!res)
             throw new ScriptError('Signature verification failed.', op, ip);
         } else {
-          stack.push(res ? new Buffer([1]) : new Buffer([]));
+          stack.push(res ? STACK_TRUE : STACK_FALSE);
         }
 
         break;
@@ -1023,7 +1026,7 @@ Script.prototype.interpret = function interpret(stack, flags, tx, index, version
           if (!res)
             throw new ScriptError('Signature verification failed.', op, ip);
         } else {
-          stack.push(res ? new Buffer([1]) : new Buffer([]));
+          stack.push(res ? STACK_TRUE : STACK_FALSE);
         }
 
         break;
@@ -1236,7 +1239,7 @@ Script.array = function(value) {
   }
 
   if (value.cmpn(0) === 0)
-    return new Buffer([]);
+    return STACK_FALSE;
 
   return value.toBuffer('le');
 };
@@ -1270,7 +1273,7 @@ Script.checkPush = function checkPush(value, flags) {
     return false;
 
   if (value.length <= 75)
-    return pushdata.opcode == null && pushdata.len === value.length;
+    return pushdata.opcode == null && pushdata.size === value.length;
 
   if (value.length <= 255)
     return pushdata.opcode === opcodes.OP_PUSHDATA1;
@@ -1859,7 +1862,7 @@ Script.isMultisigInput = function isMultisigInput(code, keys, isWitness) {
     if (!Script.isDummy(code[0]))
       return false;
   } else {
-    if (code[0] !== 0)
+    if (code[0] !== opcodes.OP_0)
       return false;
   }
 
@@ -1991,11 +1994,11 @@ Script.isDummy = function isDummy(data) {
   return data.length === 0;
 };
 
-Script.isZero = function isZero(data) {
-  if (data === 0)
+Script.isZero = function isZero(op) {
+  if (op === opcodes.OP_0)
     return true;
 
-  return Script.isDummy(data);
+  return Script.isDummy(op);
 };
 
 Script.isData = function isData(data) {
@@ -2234,13 +2237,16 @@ Script.format = function format(code) {
     if (Buffer.isBuffer(chunk))
       return '[' + utils.toHex(chunk) + ']';
 
-    if (typeof chunk === 'number') {
-      if (constants.opcodeByVal[chunk])
-        return constants.opcodesByVal[chunk].slice(3).toLowerCase();
-      return chunk;
-    }
+    assert(typeof chunk === 'number');
 
-    return chunk;
+    if (constants.opcodeByVal[chunk])
+      return constants.opcodesByVal[chunk];
+
+    chunk = chunk.toString(16);
+    if (chunk.length < 2)
+      chunk = '0' + chunk;
+
+    return 'UNKNOWN(' + chunk + ')';
   }).join(' ');
 };
 
@@ -2298,9 +2304,9 @@ Script.prototype.getArgs = function getArgs() {
     return 2;
 
   if (this.isMultisig()) {
-    keys = this.code.slice(1, -2);
+    keys = this.code.length - 3;
     m = Script.getSmall(this.code[0]);
-    if (keys.length < 1 || m < 1)
+    if (keys < 1 || m < 1)
       return -1;
     return m + 1;
   }
@@ -2367,6 +2373,13 @@ Script.fromString = function fromString(code) {
   return new Script(code);
 };
 
+Script.prototype.getSmall = function getSmall(i) {
+  if (i < 0)
+    i = this.code.length + i;
+
+  return Script.getSmall(this.code[i]);
+};
+
 Script.getSmall = function getSmall(op) {
   if (typeof op !== 'number')
     return null;
@@ -2595,17 +2608,17 @@ Script.verifyProgram = function verifyProgram(witness, output, flags, tx, i) {
 };
 
 Script.concat = function concat(scripts) {
-  var s = [];
+  var code = [];
   var i;
 
-  s = s.concat(scripts[0].code);
+  code = code.concat(scripts[0].code);
 
   for (i = 1; i < scripts.length; i++) {
-    s.push(opcodes.OP_CODESEPARATOR);
-    s = s.concat(scripts[i].code);
+    code.push(opcodes.OP_CODESEPARATOR);
+    code = code.concat(scripts[i].code);
   }
 
-  return s;
+  return code;
 };
 
 Script.checksig = function checksig(msg, sig, key, flags) {
@@ -2646,7 +2659,7 @@ Script.sign = function sign(msg, key, type) {
 Script.decode = function decode(buf) {
   var code = [];
   var off = 0;
-  var op, len;
+  var op, size;
 
   assert(Buffer.isBuffer(buf));
 
@@ -2667,7 +2680,7 @@ Script.decode = function decode(buf) {
       if (off > buf.length) {
         utils.hidden(code[code.length - 1], 'pushdata', {
           opcode: null,
-          len: op
+          size: op
         });
       }
       continue;
@@ -2679,36 +2692,36 @@ Script.decode = function decode(buf) {
     }
 
     if (op === opcodes.OP_PUSHDATA1) {
-      len = buf[off];
+      size = buf[off];
       off += 1;
-      code.push(buf.slice(off, off + len));
-      off += len;
-      if (len <= 0x4b || off > buf.length) {
+      code.push(buf.slice(off, off + size));
+      off += size;
+      if (size <= 0x4b || off > buf.length) {
         utils.hidden(code[code.length - 1], 'pushdata', {
           opcode: op,
-          len: len
+          size: size
         });
       }
     } else if (op === opcodes.OP_PUSHDATA2) {
-      len = utils.readU16(buf, off);
+      size = utils.readU16(buf, off);
       off += 2;
-      code.push(buf.slice(off, off + len));
-      off += len;
-      if (len <= 0xff || off > buf.length) {
+      code.push(buf.slice(off, off + size));
+      off += size;
+      if (size <= 0xff || off > buf.length) {
         utils.hidden(code[code.length - 1], 'pushdata', {
           opcode: op,
-          len: len
+          size: size
         });
       }
     } else if (op === opcodes.OP_PUSHDATA4) {
-      len = utils.readU32(buf, off);
+      size = utils.readU32(buf, off);
       off += 4;
-      code.push(buf.slice(off, off + len));
-      off += len;
-      if (len <= 0xffff || off > buf.length) {
+      code.push(buf.slice(off, off + size));
+      off += size;
+      if (size <= 0xffff || off > buf.length) {
         utils.hidden(code[code.length - 1], 'pushdata', {
           opcode: op,
-          len: len
+          size: size
         });
       }
     } else {
@@ -2735,19 +2748,19 @@ Script.encode = function encode(code) {
       // may have been decoded from before.
       if (op.pushdata) {
         if (op.pushdata.opcode === null) {
-          p.writeU8(op.pushdata.len);
+          p.writeU8(op.pushdata.size);
           p.writeBytes(op);
         } else if (op.pushdata.opcode === opcodes.OP_PUSHDATA1) {
           p.writeU8(opcodes.OP_PUSHDATA1);
-          p.writeU8(op.pushdata.len);
+          p.writeU8(op.pushdata.size);
           p.writeBytes(op);
         } else if (op.pushdata.opcode === opcodes.OP_PUSHDATA2) {
           p.writeU8(opcodes.OP_PUSHDATA2);
-          p.writeU16(op.pushdata.len);
+          p.writeU16(op.pushdata.size);
           p.writeBytes(op);
         } else if (op.pushdata.opcode === opcodes.OP_PUSHDATA4) {
           p.writeU8(opcodes.OP_PUSHDATA4);
-          p.writeU32(op.pushdata.len);
+          p.writeU32(op.pushdata.size);
           p.writeBytes(op);
         }
         continue;
@@ -2756,15 +2769,6 @@ Script.encode = function encode(code) {
       if (op.length === 0) {
         p.writeU8(opcodes.OP_0);
       } else if (op.length <= 0x4b) {
-        if (op.length === 1) {
-          if (op[0] === 0xff) {
-            p.writeU8(opcodes.OP_1NEGATE);
-            continue;
-          } else if (op[0] >= 0 && op[0] <= 16) {
-            p.writeU8(op[0] === 0 ? 0 : op[0] + 0x50);
-            continue;
-          }
-        }
         p.writeU8(op.length);
         p.writeBytes(op);
       } else if (op.length <= 0xff) {
diff --git a/lib/bcoin/walletdb.js b/lib/bcoin/walletdb.js
index b72d0c09..0884a082 100644
--- a/lib/bcoin/walletdb.js
+++ b/lib/bcoin/walletdb.js
@@ -176,6 +176,12 @@ WalletDB.prototype.open = function open(callback) {
   this.once('open', callback);
 };
 
+WalletDB.prototype.close =
+WalletDB.prototype.destroy = function destroy(callback) {
+  callback = utils.ensure(callback);
+  this.db.close(callback);
+};
+
 WalletDB.prototype.syncOutputDepth = function syncOutputDepth(id, tx, callback) {
   var self = this;
 
diff --git a/test/node-test.js b/test/node-test.js
index 3818a81d..597dc62f 100644
--- a/test/node-test.js
+++ b/test/node-test.js
@@ -143,4 +143,8 @@ describe('Wallet', function() {
       });
     });
   });
+
+  it('should destroy pool', function(cb) {
+    node.close(cb);
+  });
 });