diff --git a/lib/bcoin/address.js b/lib/bcoin/address.js
index a899b740..4a8e1685 100644
--- a/lib/bcoin/address.js
+++ b/lib/bcoin/address.js
@@ -54,6 +54,12 @@ function Address(options) {
   }, this);
 }
 
+Address.isAddress = function isAddress(obj) {
+  return obj
+    && Array.isArray(obj.keys)
+    && typeof obj._getAddressMap === 'function';
+};
+
 Address.prototype.getID = function getID() {
   return this.getKeyAddress();
 };
diff --git a/lib/bcoin/block.js b/lib/bcoin/block.js
index 24ce2570..68211182 100644
--- a/lib/bcoin/block.js
+++ b/lib/bcoin/block.js
@@ -420,6 +420,12 @@ Block.fromCompact = function fromCompact(buf) {
   };
 };
 
+Block.isBlock = function isBlock(obj) {
+  return obj
+    && typeof obj.merkleRoot === 'string'
+    && typeof obj.toCompact === 'function';
+};
+
 /**
  * Expose
  */
diff --git a/lib/bcoin/chainblock.js b/lib/bcoin/chainblock.js
index e2d00600..bf398581 100644
--- a/lib/bcoin/chainblock.js
+++ b/lib/bcoin/chainblock.js
@@ -302,6 +302,12 @@ ChainBlock.prototype.inspect = function inspect() {
   return json;
 };
 
+ChainBlock.isChainBlock = function isChainBlock(obj) {
+  return obj
+    && bn.isBN(obj.chainwork)
+    && typeof obj.getMedianTime === 'function';
+};
+
 /**
  * Expose
  */
diff --git a/lib/bcoin/coin.js b/lib/bcoin/coin.js
index ff92de0c..d51a66fb 100644
--- a/lib/bcoin/coin.js
+++ b/lib/bcoin/coin.js
@@ -54,7 +54,7 @@ function Coin(tx, index) {
 
   assert(typeof this.version === 'number');
   assert(utils.isFinite(this.height));
-  assert(this.value instanceof bn);
+  assert(bn.isBN(this.value));
   assert(this.script instanceof bcoin.script);
   assert(typeof this.coinbase === 'boolean');
   // assert(typeof this.hash === 'string');
@@ -198,6 +198,13 @@ Coin.fromExtended = function fromExtended(data, enc) {
   return new Coin(Coin._fromExtended(data, enc));
 };
 
+Coin.isCoin = function isCoin(obj) {
+  return obj
+    && typeof obj.version === 'number'
+    && typeof obj.script === 'object'
+    && typeof obj.getConfirmations === 'function';
+};
+
 /**
  * Expose
  */
diff --git a/lib/bcoin/hd.js b/lib/bcoin/hd.js
index 0a72666b..f30b1c29 100644
--- a/lib/bcoin/hd.js
+++ b/lib/bcoin/hd.js
@@ -112,6 +112,12 @@ HDSeed.prototype.createMnemonic = function createMnemonic(entropy) {
   return mnemonic.join(' ');
 };
 
+HDSeed.isHDSeed = function isHDSeed(obj) {
+  return obj
+    && typeof obj.bits === 'number'
+    && typeof obj.createSeed === 'function';
+};
+
 /**
  * Abstract
  */
@@ -130,6 +136,10 @@ HD.fromSeed = function fromSeed(options) {
 
 HD.cache = new LRU(500);
 
+HD.isHD = function isHD(obj) {
+  return HDPrivateKey.isHDPrivateKey(obj) || HDPublicKey.isHDPublicKey(obj);
+};
+
 /**
  * HD Private Key
  */
@@ -184,6 +194,10 @@ function HDPrivateKey(options) {
   this.isPublic = false;
 }
 
+HDPublicKey.isHDPrivateKey = function isHDPrivateKey(obj) {
+  return obj && obj.isPrivate && typeof obj._unbuild === 'function';
+};
+
 utils.inherits(HDPrivateKey, HD);
 
 HDPrivateKey.prototype.deriveAccount44 = function deriveAccount44(options) {
@@ -809,6 +823,10 @@ function HDPublicKey(options) {
 
 utils.inherits(HDPublicKey, HD);
 
+HDPublicKey.isHDPublicKey = function isHDPublicKey(obj) {
+  return obj && obj.isPublic && typeof obj._unbuild === 'function';
+};
+
 HDPublicKey.prototype.scan44 = HDPrivateKey.prototype.scan44;
 HDPublicKey.prototype.deriveAccount44 = HDPrivateKey.prototype.deriveAccount44;
 HDPublicKey.prototype.deriveBIP44 = HDPrivateKey.prototype.deriveBIP44;
diff --git a/lib/bcoin/headers.js b/lib/bcoin/headers.js
index d7a092ec..3548a3c3 100644
--- a/lib/bcoin/headers.js
+++ b/lib/bcoin/headers.js
@@ -18,26 +18,32 @@ function Headers(data) {
   bcoin.abstractblock.call(this, data);
 
   this.type = 'headers';
-
-  if (!this._raw)
-    this._raw = this.render();
-
-  if (!this._size)
-    this._size = this._raw.length;
 }
 
 utils.inherits(Headers, bcoin.abstractblock);
 
 Headers.prototype.render = function render() {
-  if (this._raw)
-    return this._raw;
-  return bcoin.protocol.framer.headers(this);
+  return this.getRaw();
 };
 
 Headers.prototype._verify = function _verify() {
   return this.verifyHeaders();
 };
 
+Headers.prototype.getSize = function getSize() {
+  if (this._size == null)
+    this.getRaw();
+  return this._size;
+};
+
+Headers.prototype.getRaw = function getRaw() {
+  if (!this._raw) {
+    this._raw = bcoin.protocol.framer.headers(this);
+    this._size = this._raw.length;
+  }
+  return this._raw;
+};
+
 Headers.prototype.inspect = function inspect() {
   var copy = bcoin.headers(this);
   copy.__proto__ = null;
@@ -71,6 +77,9 @@ Headers.fromRaw = function fromRaw(data, enc) {
   return new Headers(Headers._fromRaw(data, enc));
 };
 
+Headers.isHeaders = function isHeaders(obj) {
+  return obj && obj.type === 'headers' && typeof obj.render === 'function';
+};
 
 /**
  * Expose
diff --git a/lib/bcoin/input.js b/lib/bcoin/input.js
index 5ebad7ef..ffc1a624 100644
--- a/lib/bcoin/input.js
+++ b/lib/bcoin/input.js
@@ -303,6 +303,14 @@ Input.fromExtended = function fromExtended(data, enc) {
   return new Input(Input._fromExtended(data, enc));
 };
 
+Input.isInput = function isInput(obj) {
+  return obj
+    && obj.prevout
+    && obj.script
+    && obj.witness
+    && typeof obj.getAddress === 'function';
+};
+
 /**
  * Expose
  */
diff --git a/lib/bcoin/merkleblock.js b/lib/bcoin/merkleblock.js
index ded95e47..57e6c08e 100644
--- a/lib/bcoin/merkleblock.js
+++ b/lib/bcoin/merkleblock.js
@@ -35,9 +35,21 @@ function MerkleBlock(data) {
 utils.inherits(MerkleBlock, bcoin.abstractblock);
 
 MerkleBlock.prototype.render = function render() {
-  if (this._raw)
-    return this._raw;
-  return bcoin.protocol.framer.merkleBlock(this);
+  return this.getRaw();
+};
+
+MerkleBlock.prototype.getSize = function getSize() {
+  if (this._size == null)
+    this.getRaw();
+  return this._size;
+};
+
+MerkleBlock.prototype.getRaw = function getRaw() {
+  if (!this._raw) {
+    this._raw = bcoin.protocol.framer.merkleBlock(this);
+    this._size = this._raw.length;
+  }
+  return this._raw;
 };
 
 MerkleBlock.prototype.hasTX = function hasTX(hash) {
@@ -154,6 +166,12 @@ MerkleBlock.fromRaw = function fromRaw(data, enc) {
   return new MerkleBlock(MerkleBlock._fromRaw(data, enc));
 };
 
+MerkleBlock.isMerkleBlock = function isMerkleBlock(obj) {
+  return obj
+    && Array.isArray(obj.flags)
+    && typeof obj._verifyPartial === 'function';
+};
+
 /**
  * Expose
  */
diff --git a/lib/bcoin/mtx.js b/lib/bcoin/mtx.js
index 52b667c6..13a8cb90 100644
--- a/lib/bcoin/mtx.js
+++ b/lib/bcoin/mtx.js
@@ -1118,6 +1118,14 @@ MTX.prototype.toTX = function toTX() {
   return new bcoin.tx(this);
 };
 
+MTX.isMTX = function isMTX(obj) {
+  return obj
+    && Array.isArray(obj.inputs)
+    && typeof obj.ps === 'number'
+    && typeof obj.changeIndex === 'number'
+    && typeof obj.scriptInput === 'function';
+};
+
 /**
  * Expose
  */
diff --git a/lib/bcoin/output.js b/lib/bcoin/output.js
index 5e038df3..b174f1a4 100644
--- a/lib/bcoin/output.js
+++ b/lib/bcoin/output.js
@@ -151,6 +151,13 @@ Output.fromRaw = function fromRaw(data, enc) {
   return new Output(Output._fromRaw(data, enc));
 };
 
+Output.isOutput = function isOutput(obj) {
+  return obj
+    && obj.value
+    && obj.script
+    && typeof obj.getAddress === 'function';
+};
+
 /**
  * Expose
  */
diff --git a/lib/bcoin/script.js b/lib/bcoin/script.js
index dd61ee72..505a81a9 100644
--- a/lib/bcoin/script.js
+++ b/lib/bcoin/script.js
@@ -125,6 +125,12 @@ Witness.fromString = function fromString(items) {
   return new Witness(items);
 };
 
+Witness.isWitness = function isWitness(obj) {
+  return obj
+    && Array.isArray(obj.items)
+    && typeof obj.toStack === 'function';
+};
+
 function Stack(items) {
   this.items = items || [];
   this.alt = [];
@@ -388,6 +394,10 @@ Stack.prototype.size = function size() {
   this.push(Script.array(this.top(-1).length));
 };
 
+Stack.isStack = function isStack(obj) {
+  return obj && Array.isArray(obj.alt) && typeof obj.swap2 === 'function';
+};
+
 /**
  * Script
  */
@@ -1106,7 +1116,7 @@ Script.bool = function bool(value) {
   // if (utils.isFinite(value))
   //   return value !== 0;
 
-  if (value instanceof bn)
+  if (bn.isBN(value))
     return value.cmpn(0) !== 0;
 
   assert(Buffer.isBuffer(value));
@@ -1174,7 +1184,7 @@ Script.array = function(value) {
   if (utils.isFinite(value))
     value = new bn(value, 'le');
 
-  assert(value instanceof bn);
+  assert(bn.isBN(value));
 
   // Convert the number to the
   // negative byte representation.
@@ -1231,7 +1241,7 @@ Script.checkPush = function checkPush(value, flags) {
   return true;
 };
 
-Script.isScript = function isScript(buf) {
+Script.isCode = function isCode(buf) {
   var i, b;
 
   if (!buf)
@@ -1872,7 +1882,7 @@ Script.isScripthashInput = function isScripthashInput(code, redeem, isWitness) {
   if (Script.isKeyEncoding(raw))
     return false;
 
-  if (!Script.isScript(raw))
+  if (!Script.isCode(raw))
     return false;
 
   return true;
@@ -2676,6 +2686,12 @@ Script.encode = function encode(code) {
   return p.render();
 };
 
+Script.isScript = function isScript(obj) {
+  return obj
+    && Array.isArray(obj.code)
+    && typeof obj.getSubscript === 'function';
+};
+
 Script.witness = Witness;
 Script.stack = Stack;
 module.exports = Script;
diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index cfc4a640..592307c7 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -1259,6 +1259,13 @@ TX.prototype.toCoins = function toCoins() {
   return bcoin.coins.fromTX(this);
 };
 
+TX.isTX = function isTX(obj) {
+  return obj
+    && Array.isArray(obj.inputs)
+    && typeof obj.ps === 'number'
+    && typeof obj.getVirtualSize === 'function';
+};
+
 /**
  * Expose
  */
diff --git a/lib/bcoin/utils.js b/lib/bcoin/utils.js
index 144557a5..40571777 100644
--- a/lib/bcoin/utils.js
+++ b/lib/bcoin/utils.js
@@ -606,7 +606,7 @@ utils.isFinite = function _isFinite(val) {
 };
 
 utils.isSatoshi = function isSatoshi(val) {
-  if (val instanceof bn)
+  if (bn.isBN(val))
     return val;
   if (utils.isInt(val))
     return new bn(val, 10);
@@ -1192,7 +1192,7 @@ utils.writeU32BE = function writeU32BE(dst, num, off) {
 utils.writeU64 = function writeU64(dst, num, off) {
   var i;
 
-  if (!(num instanceof bn))
+  if (!bn.isBN(num))
     num = new bn(+num);
 
   off = off >>> 0;
@@ -1218,7 +1218,7 @@ utils.writeU64 = function writeU64(dst, num, off) {
 utils.writeU64BE = function writeU64BE(dst, num, off) {
   var i;
 
-  if (!(num instanceof bn))
+  if (!bn.isBN(num))
     num = new bn(+num);
 
   off = off >>> 0;
@@ -1244,7 +1244,7 @@ utils.writeU64BE = function writeU64BE(dst, num, off) {
 utils.writeU256 = function writeU256(dst, num, off) {
   var i;
 
-  if (!(num instanceof bn))
+  if (!bn.isBN(num))
     num = new bn(+num);
 
   off = off >>> 0;
@@ -1267,7 +1267,7 @@ utils.writeU256 = function writeU256(dst, num, off) {
 utils.writeU256BE = function writeU256BE(dst, num, off) {
   var i;
 
-  if (!(num instanceof bn))
+  if (!bn.isBN(num))
     num = new bn(+num);
 
   off = off >>> 0;
@@ -1333,7 +1333,7 @@ utils.write32BE = function write32BE(dst, num, off) {
 utils.write64 = function write64(dst, num, off) {
   var i;
 
-  if (!(num instanceof bn))
+  if (!bn.isBN(num))
     num = new bn(+num);
 
   off = off >>> 0;
@@ -1363,7 +1363,7 @@ utils.write64 = function write64(dst, num, off) {
 utils.write64BE = function write64BE(dst, num, off) {
   var i;
 
-  if (!(num instanceof bn))
+  if (!bn.isBN(num))
     num = new bn(+num);
 
   off = off >>> 0;
@@ -1423,7 +1423,7 @@ utils.readIntv = function readIntv(arr, off) {
 utils.writeIntv = function writeIntv(dst, num, off) {
   off = off >>> 0;
 
-  if (num instanceof bn) {
+  if (bn.isBN(num)) {
     if (num.cmpn(0xffffffff) > 0) {
       dst[off] = 0xff;
       utils.writeU64(dst, num, off + 1);
@@ -1461,7 +1461,7 @@ utils.writeIntv = function writeIntv(dst, num, off) {
 };
 
 utils.sizeIntv = function sizeIntv(num) {
-  if (num instanceof bn) {
+  if (bn.isBN(num)) {
     if (num.cmpn(0xffffffff) > 0)
       return 9;
     num = num.toNumber();
diff --git a/lib/bcoin/wallet.js b/lib/bcoin/wallet.js
index b5e62ba3..5aaca8ee 100644
--- a/lib/bcoin/wallet.js
+++ b/lib/bcoin/wallet.js
@@ -40,12 +40,8 @@ function Wallet(options) {
 
   this.options = options;
   this.provider = options.provider || null;
-  this.addresses = [];
   this.master = options.master || null;
   this.addressMap = options.addressMap || {};
-  this.labelMap = {};
-  this.change = [];
-  this.receive = [];
   this.witness = options.witness || false;
   this.loaded = false;
 
@@ -1091,6 +1087,12 @@ Wallet.setDepth = function setDepth(json, receiveDepth, changeDepth) {
   });
 };
 
+Wallet.isWallet = function isWallet(obj) {
+  return obj
+    && typeof obj.receiveDepth === 'number'
+    && obj.deriveAddress === 'function';
+};
+
 /**
  * Expose
  */
diff --git a/lib/bcoin/workers.js b/lib/bcoin/workers.js
index 56a89e18..248e008d 100644
--- a/lib/bcoin/workers.js
+++ b/lib/bcoin/workers.js
@@ -214,7 +214,7 @@ function frameItem(item, p) {
         } else if (item instanceof bcoin.coin) {
           p.writeU8(42);
           p.writeVarBytes(item.toExtended());
-        } else if (item instanceof bn) {
+        } else if (bn.isBN(item)) {
           p.writeU8(43);
           p.writeVarBytes(item.toBuffer());
         } else if (Buffer.isBuffer(item)) {
diff --git a/package.json b/package.json
index ba6ae7ef..f8fa6536 100644
--- a/package.json
+++ b/package.json
@@ -28,9 +28,10 @@
     "node": ">= 0.8.0"
   },
   "dependencies": {
-    "bn.js": "4.10.3",
-    "elliptic": "6.0.2",
-    "leveldown": "1.4.4"
+    "bn.js": "4.11.0",
+    "elliptic": "6.2.3",
+    "leveldown": "git://github.com/Level/leveldown.git#master",
+    "memdown": "1.1.2"
   },
   "optionalDependencies": {
     "secp256k1": "3.0.0",