diff --git a/lib/bcoin/hd.js b/lib/bcoin/hd.js
index b84fc032..8e1a54ab 100644
--- a/lib/bcoin/hd.js
+++ b/lib/bcoin/hd.js
@@ -238,6 +238,17 @@ HD.fromAny = function fromAny(options, networkType) {
   return HDPrivateKey.fromSeed(options, networkType);
 };
 
+/**
+ * Test whether an object is in the form of a base58 hd key.
+ * @param {String} data
+ * @returns {Boolean}
+ */
+
+HD.isExtended = function isExtended(data) {
+  return HDPrivateKey.isExtended(data)
+    || HDPublicKey.isExtended(data);
+};
+
 /**
  * LRU cache to avoid deriving keys twice.
  * @type {LRU}
diff --git a/lib/bcoin/wallet.js b/lib/bcoin/wallet.js
index 5aa36c8f..da84ed05 100644
--- a/lib/bcoin/wallet.js
+++ b/lib/bcoin/wallet.js
@@ -44,9 +44,6 @@ var assert = utils.assert;
 var constants = bcoin.protocol.constants;
 var network = bcoin.protocol.network;
 var BufferWriter = require('./writer');
-var HD = bcoin.hd;
-var HDPrivateKey = bcoin.hd.privateKey;
-var HDPublicKey = bcoin.hd.publicKey;
 
 /**
  * HD BIP-44/45 wallet
@@ -98,12 +95,12 @@ function Wallet(options) {
 
   if (options.master
       && typeof options.master === 'object'
-      && !(options.master instanceof HD)) {
-    options.master = HD.fromAny(options.master);
+      && !(options.master instanceof bcoin.hd)) {
+    options.master = bcoin.hd.fromAny(options.master);
   }
 
   if (!options.master)
-    options.master = HD.fromSeed();
+    options.master = bcoin.hd.fromSeed();
 
   this.options = options;
   this.provider = options.provider || null;
@@ -272,20 +269,20 @@ Wallet.prototype.destroy = function destroy(callback) {
 Wallet.prototype.addKey = function addKey(key) {
   var index, i;
 
+  assert(key, 'Key required.');
+
   if (key instanceof bcoin.wallet) {
     assert(key.derivation === this.derivation);
     key = key.accountKey;
   }
 
-  if (HDPrivateKey.isExtended(key))
-    key = HDPrivateKey.fromBase58(key);
-  else if (HDPublicKey.isExtended(key))
-    key = HDPublicKey.fromBase58(key);
+  if (bcoin.hd.isExtended(key))
+    key = bcoin.hd.fromBase58(key);
 
-  if (key instanceof HDPrivateKey)
+  if (key.hdPublicKey)
     key = key.hdPublicKey;
 
-  assert(key instanceof HD, 'Must add HD keys to wallet.');
+  assert(key instanceof bcoin.hd, 'Must add HD keys to wallet.');
 
   if (this.derivation === 'bip44') {
     if (!key || !key.isAccount44())
@@ -325,20 +322,20 @@ Wallet.prototype.removeKey = function removeKey(key) {
 
   assert(!this._keysFinalized);
 
+  assert(key, 'Key required.');
+
   if (key instanceof bcoin.wallet) {
     assert(key.derivation === this.derivation);
     key = key.accountKey;
   }
 
-  if (HDPrivateKey.isExtended(key))
-    key = HDPrivateKey.fromBase58(key);
-  else if (HDPublicKey.isExtended(key))
-    key = HDPublicKey.fromBase58(key);
+  if (bcoin.hd.isExtended(key))
+    key = bcoin.hd.fromBase58(key);
 
-  if (key instanceof HDPrivateKey)
+  if (key.hdPublicKey)
     key = key.hdPublicKey;
 
-  assert(key instanceof HD, 'Must add HD keys to wallet.');
+  assert(key instanceof bcoin.hd, 'Must add HD keys to wallet.');
 
   if (this.derivation === 'bip44') {
     if (!key || !key.isAccount44())