diff --git a/lib/ecdsa.js b/lib/ecdsa.js
index 6c90e162d..c5fe9082c 100644
--- a/lib/ecdsa.js
+++ b/lib/ecdsa.js
@@ -6,14 +6,20 @@ var Privkey = require('./privkey');
 var Pubkey = require('./pubkey');
 var Random = require('./random');
 
-var ECDSA = function ECDSA(hashbuf, key, sig, k, verified) {
+var ECDSA = function ECDSA(obj) {
   if (!(this instanceof ECDSA))
-    return new ECDSA(hashbuf, key, sig, k, verified);
-  this.hashbuf = hashbuf;
-  this.key = key;
-  this.sig = sig;
-  this.k = k;
-  this.verified = verified;
+    return new ECDSA(obj);
+  if (obj)
+    this.set(obj);
+};
+
+ECDSA.prototype.set = function(obj) {
+  this.hashbuf = obj.hashbuf || this.hashbuf || undefined;
+  this.key = obj.key || this.key || undefined;
+  this.sig = obj.sig || this.sig || undefined;
+  this.k = obj.k || this.k || undefined;
+  this.verified = obj.verified || this.verified || undefined;
+  return this;
 };
 
 ECDSA.prototype.calci = function() {
diff --git a/lib/message.js b/lib/message.js
index c345dfb3d..6e4bcb914 100644
--- a/lib/message.js
+++ b/lib/message.js
@@ -54,7 +54,7 @@ Message.verify = function(messagebuf, sigstr, address) {
 
 Message.prototype.sign = function() {
   var hashbuf = Message.magicHash(this.messagebuf);
-  var ecdsa = ECDSA(hashbuf, this.key);
+  var ecdsa = ECDSA({hashbuf: hashbuf, key: this.key});
   ecdsa.signRandomK();
   ecdsa.calci();
   this.sig = ecdsa.sig;
diff --git a/test/test.ecdsa.js b/test/test.ecdsa.js
index 76886f4c5..f17a8a43f 100644
--- a/test/test.ecdsa.js
+++ b/test/test.ecdsa.js
@@ -21,6 +21,14 @@ describe("ECDSA", function() {
   ecdsa.key.pubkey = new Pubkey(point(BN().fromBuffer(new Buffer('ac242d242d23be966085a2b2b893d989f824e06c9ad0395a8a52f055ba39abb2', 'hex')),
                                       BN().fromBuffer(new Buffer('4836ab292c105a711ed10fcfd30999c31ff7c02456147747e03e739ad527c380', 'hex'))));
 
+  describe('#set', function() {
+    
+    it('should set hashbuf', function() {
+      should.exist(ECDSA().set({hashbuf: ecdsa.hashbuf}).hashbuf);
+    });
+
+  });
+
   describe('#calci', function() {
     
     it('should calculate i', function() {