diff --git a/src/bip32.js b/src/bip32.js
index 4c04952..306550a 100644
--- a/src/bip32.js
+++ b/src/bip32.js
@@ -116,7 +116,7 @@ BIP32key.prototype.privtopub = BIP32key.prototype.getPub = function() {
 }
 
 BIP32key.fromMasterKey = function(seed) {
-    var I = Bitcoin.Crypto.HMAC(Bitcoin.Crypto.SHA512,seed, 'Bitcoin seed' , { asBytes: true })
+    var I = Crypto.HMAC(Crypto.SHA512,seed, 'Bitcoin seed' , { asBytes: true })
     return new BIP32key({
         vbytes: conv.stringToBytes(PRIVDERIV),
         type: 'priv',