diff --git a/lib/hdprivatekey.js b/lib/hdprivatekey.js
index 7a2ca00..262f37d 100644
--- a/lib/hdprivatekey.js
+++ b/lib/hdprivatekey.js
@@ -52,6 +52,8 @@ function HDPrivateKey(arg) {
       this._buildFromSerialized(arg);
     } else if (JSUtil.isValidJSON(arg)) {
       this._buildFromJSON(arg);
+    } else if (BufferUtil.isBuffer(arg) && HDPrivateKey.isValidSerialized(arg.toString())) {
+      this._buildFromSerialized(arg.toString());
     } else {
       throw HDPrivateKey.getSerializedError(arg);
     }
@@ -377,12 +379,8 @@ HDPrivateKey.prototype._buildFromBuffers = function(arg) {
   }
 
   var xprivkey;
-
-  if (!arg.xprivkey) {
-    xprivkey = Base58Check.encode(buffer.Buffer.concat(sequence));
-  } else {
-    xprivkey = arg.xprivkey;
-  }
+  xprivkey = Base58Check.encode(buffer.Buffer.concat(sequence));
+  arg.xprivkey = new Buffer(xprivkey);
 
   var privateKey = new PrivateKey(BN.fromBuffer(arg.privateKey));
   var publicKey = privateKey.toPublicKey();
@@ -496,7 +494,7 @@ HDPrivateKey.prototype.toJSON = function toJSON() {
  * @return {HDPrivateKey}
  */
 HDPrivateKey.fromBuffer = function(arg) {
-  return new HDPrivateKey(arg);
+  return new HDPrivateKey(arg.toString());
 };
 
 /**
@@ -505,7 +503,7 @@ HDPrivateKey.fromBuffer = function(arg) {
  * @return {string}
  */
 HDPrivateKey.prototype.toBuffer = function() {
-  return this._buffers.xprivkey;
+  return BufferUtil.copy(this._buffers.xprivkey);
 };
 
 HDPrivateKey.DefaultDepth = 0;
diff --git a/lib/hdpublickey.js b/lib/hdpublickey.js
index 7126d50..7b38fdd 100644
--- a/lib/hdpublickey.js
+++ b/lib/hdpublickey.js
@@ -43,6 +43,8 @@ function HDPublicKey(arg) {
         return this._buildFromSerialized(arg);
       } else if (JSUtil.isValidJSON(arg)) {
         return this._buildFromJSON(arg);
+      } else if (BufferUtil.isBuffer(arg) && !HDPublicKey.getSerializedError(arg.toString())) {
+        return this._buildFromSerialized(arg.toString());
       } else {
         if (error instanceof hdErrors.ArgumentIsPrivateExtended) {
           return new HDPrivateKey(arg).hdPublicKey;
@@ -316,12 +318,8 @@ HDPublicKey.prototype._buildFromBuffers = function (arg) {
   }
 
   var xpubkey;
-
-  if (!arg.xpubkey) {
-    xpubkey = Base58Check.encode(BufferUtil.concat(sequence));
-  } else {
-    xpubkey = arg.xpubkey;
-  }
+  xpubkey = Base58Check.encode(BufferUtil.concat(sequence));
+  arg.xpubkey = new Buffer(xpubkey);
 
   var publicKey = PublicKey.fromString(arg.publicKey);
   var size = HDPublicKey.ParentFingerPrintSize;
@@ -433,7 +431,7 @@ HDPublicKey.fromBuffer = function(arg) {
  * @return {Buffer}
  */
 HDPublicKey.prototype.toBuffer = function() {
-  return this._buffers.xpubkey;
+  return BufferUtil.copy(this._buffers.xpubkey);
 };
 
 HDPublicKey.Hardened = 0x80000000;
diff --git a/lib/util/buffer.js b/lib/util/buffer.js
index f750b5e..332b4be 100644
--- a/lib/util/buffer.js
+++ b/lib/util/buffer.js
@@ -37,6 +37,18 @@ module.exports = {
     return buffer;
   },
 
+  /**
+   * Return a copy of a buffer
+   *
+   * @param {Buffer} original
+   * @return {Buffer}
+   */
+  copy: function(original) {
+    var buffer = new Buffer(original.length);
+    original.copy(buffer);
+    return buffer;
+  },
+
   /**
    * Returns true if the given argument is an instance of a buffer. Tests for
    * both node's Buffer and Uint8Array