diff --git a/lib/bcoin/hd.js b/lib/bcoin/hd.js
index 9e0863c5..c645c1bd 100644
--- a/lib/bcoin/hd.js
+++ b/lib/bcoin/hd.js
@@ -662,25 +662,31 @@ HDPrivateKey.prototype._unbuild = function _unbuild(xkey) {
   else
     this.network = 'testnet';
 
+  this.xprivkey = xkey;
+
   return data;
 };
 
 HDPrivateKey.prototype._build = function _build(data) {
-  var sequence = new Buffer(82);
   var off = 0;
-  var checksum;
+  var sequence, checksum;
 
-  off += utils.copy(data.version, sequence, off);
-  off += utils.copy(data.depth, sequence, off);
-  off += utils.copy(data.parentFingerPrint, sequence, off);
-  off += utils.copy(data.childIndex, sequence, off);
-  off += utils.copy(data.chainCode, sequence, off);
-  off += utils.writeU8(sequence, 0, off);
-  off += utils.copy(data.privateKey, sequence, off);
-  assert(off === 78, off);
-  checksum = utils.dsha256(sequence.slice(0, off)).slice(0, 4);
-  off += utils.copy(checksum, sequence, off);
-  assert(off === 82, off);
+  if (!this.xprivkey) {
+    sequence = new Buffer(82);
+    off += utils.copy(data.version, sequence, off);
+    off += utils.copy(data.depth, sequence, off);
+    off += utils.copy(data.parentFingerPrint, sequence, off);
+    off += utils.copy(data.childIndex, sequence, off);
+    off += utils.copy(data.chainCode, sequence, off);
+    off += utils.writeU8(sequence, 0, off);
+    off += utils.copy(data.privateKey, sequence, off);
+    assert(off === 78, off);
+    checksum = utils.dsha256(sequence.slice(0, off)).slice(0, 4);
+    off += utils.copy(checksum, sequence, off);
+    assert(off === 82, off);
+
+    this.xprivkey = utils.toBase58(sequence);
+  }
 
   this.version = data.version;
   this.depth = data.depth;
@@ -694,7 +700,6 @@ HDPrivateKey.prototype._build = function _build(data) {
   this.fingerPrint = null;
 
   this.hdPrivateKey = this;
-  this.xprivkey = utils.toBase58(sequence);
 
   this.hdPublicKey = new HDPublicKey({
     network: this.network,
@@ -1026,29 +1031,35 @@ HDPublicKey.prototype._unbuild = function _unbuild(xkey) {
   else
     this.network = 'testnet';
 
+  this.xpubkey = xkey;
+
   return data;
 };
 
 HDPublicKey.prototype._build = function _build(data) {
-  var sequence = new Buffer(82);
   var off = 0;
-  var checksum;
+  var sequence, checksum;
 
-  off += utils.copy(data.version, sequence, off);
-  off += utils.copy(data.depth, sequence, off);
-  off += utils.copy(data.parentFingerPrint, sequence, off);
-  off += utils.copy(data.childIndex, sequence, off);
-  off += utils.copy(data.chainCode, sequence, off);
-  off += utils.copy(data.publicKey, sequence, off);
-  assert(off === 78, off);
-  checksum = utils.dsha256(sequence.slice(0, off)).slice(0, 4);
-  off += utils.copy(checksum, sequence, off);
-  assert(off === 82, off);
+  if (!this.xpubkey) {
+    sequence = new Buffer(82);
+    off += utils.copy(data.version, sequence, off);
+    off += utils.copy(data.depth, sequence, off);
+    off += utils.copy(data.parentFingerPrint, sequence, off);
+    off += utils.copy(data.childIndex, sequence, off);
+    off += utils.copy(data.chainCode, sequence, off);
+    off += utils.copy(data.publicKey, sequence, off);
+    assert(off === 78, off);
+    checksum = utils.dsha256(sequence.slice(0, off)).slice(0, 4);
+    off += utils.copy(checksum, sequence, off);
+    assert(off === 82, off);
 
-  if (!data.checksum || !data.checksum.length)
-    data.checksum = checksum;
-  else if (utils.toHex(checksum) !== utils.toHex(data.checksum))
-    throw new Error('checksum mismatch');
+    if (!data.checksum || !data.checksum.length)
+      data.checksum = checksum;
+    else if (utils.toHex(checksum) !== utils.toHex(data.checksum))
+      throw new Error('checksum mismatch');
+
+    this.xpubkey = utils.toBase58(sequence);
+  }
 
   this.version = data.version;
   this.depth = data.depth;
@@ -1062,7 +1073,6 @@ HDPublicKey.prototype._build = function _build(data) {
   this.fingerPrint = null;
 
   this.hdPublicKey = this;
-  this.xpubkey = utils.toBase58(sequence);
 
   this.hdPrivateKey = null;
   this.xprivkey = null;