diff --git a/lib/crypto/crypto.js b/lib/crypto/crypto.js
index 9447ff08..3575e0d1 100644
--- a/lib/crypto/crypto.js
+++ b/lib/crypto/crypto.js
@@ -126,14 +126,6 @@ crypto.checksum = function checksum(data) {
 crypto.hmac = function hmac(alg, data, salt) {
   var hmac;
 
-  if (native) {
-    if (typeof data === 'string')
-      data = new Buffer(data, 'utf8');
-    if (typeof salt === 'string')
-      salt = new Buffer(salt, 'utf8');
-    return native.hmac(alg, data, salt);
-  }
-
   if (!nativeCrypto) {
     hmac = hash.hmac(hash[alg], salt);
     return new Buffer(hmac.update(data).digest());
@@ -143,6 +135,9 @@ crypto.hmac = function hmac(alg, data, salt) {
   return hmac.update(data).digest();
 };
 
+if (native)
+  crypto.hmac = native.hmac;
+
 /**
  * Perform key stretching using PBKDF2.
  * @param {Buffer} key
diff --git a/lib/hd/private.js b/lib/hd/private.js
index 846c42b2..1cb33861 100644
--- a/lib/hd/private.js
+++ b/lib/hd/private.js
@@ -23,6 +23,7 @@ var HD = require('./hd');
  */
 
 var FINGER_PRINT = new Buffer('00000000', 'hex');
+var SEED_SALT = new Buffer('Bitcoin seed', 'ascii');
 
 /**
  * HDPrivateKey
@@ -481,7 +482,7 @@ HDPrivateKey.prototype.fromSeed = function fromSeed(seed, network) {
     throw new Error('Entropy not in range.');
   }
 
-  hash = crypto.hmac('sha512', seed, 'Bitcoin seed');
+  hash = crypto.hmac('sha512', seed, SEED_SALT);
 
   left = hash.slice(0, 32);
   right = hash.slice(32, 64);