diff --git a/lib/bufferreader.js b/lib/bufferreader.js
index 35a305c..cf6b891 100644
--- a/lib/bufferreader.js
+++ b/lib/bufferreader.js
@@ -1,10 +1,16 @@
 var BN = require('./bn');
 
-var BufferReader = function BufferReader(buf, pos) {
+var BufferReader = function BufferReader(obj) {
   if (!(this instanceof BufferReader))
-    return new BufferReader(buf);
-  this.buf = buf;
-  this.pos = pos || 0;
+    return new BufferReader(obj);
+  if (obj)
+    this.set(obj);
+};
+
+BufferReader.prototype.set = function(obj) {
+  this.buf = obj.buf || this.buf || undefined;
+  this.pos = obj.pos || this.pos || 0;
+  return this;
 };
 
 BufferReader.prototype.eof = function eof() {
@@ -56,7 +62,7 @@ BufferReader.prototype.readUInt64BEBN = function() {
 
 BufferReader.prototype.readUInt64LEBN = function() {
   var buf = this.buf.slice(this.pos, this.pos + 8);
-  var reversebuf = BufferReader(buf).reverse().read();
+  var reversebuf = BufferReader({buf: buf}).reverse().read();
   var bn = BN().fromBuffer(reversebuf);
   this.pos = this.pos + 8;
   return bn;
diff --git a/test/test.bufferreader.js b/test/test.bufferreader.js
index cf0a25e..d4ffdb3 100644
--- a/test/test.bufferreader.js
+++ b/test/test.bufferreader.js
@@ -9,10 +9,18 @@ describe('BufferReader', function() {
     should.exist(br);
   });
 
+  describe('#set', function() {
+
+    it('should set pos', function() {
+      should.exist(BufferReader().set({pos: 1}).pos);
+    });
+
+  });
+
   describe('#eof', function() {
 
     it('should return true for a blank br', function() {
-      var br = new BufferReader(new Buffer([]));
+      var br = new BufferReader({buf: new Buffer([])});
       br.eof().should.equal(true);
     });
 
@@ -22,7 +30,7 @@ describe('BufferReader', function() {
     
     it('should return the same buffer', function() {
       var buf = new Buffer([0]);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.read().toString('hex').should.equal(buf.toString('hex'));
     });
 
@@ -33,7 +41,7 @@ describe('BufferReader', function() {
     it('should return 1', function() {
       var buf = new Buffer(1);
       buf.writeUInt8(1, 0);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readUInt8().should.equal(1);
     });
 
@@ -44,7 +52,7 @@ describe('BufferReader', function() {
     it('should return 1', function() {
       var buf = new Buffer(2);
       buf.writeUInt16BE(1, 0);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readUInt16BE().should.equal(1);
     });
 
@@ -55,7 +63,7 @@ describe('BufferReader', function() {
     it('should return 1', function() {
       var buf = new Buffer(2);
       buf.writeUInt16LE(1, 0);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readUInt16LE().should.equal(1);
     });
 
@@ -66,7 +74,7 @@ describe('BufferReader', function() {
     it('should return 1', function() {
       var buf = new Buffer(4);
       buf.writeUInt32BE(1, 0);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readUInt32BE().should.equal(1);
     });
 
@@ -77,7 +85,7 @@ describe('BufferReader', function() {
     it('should return 1', function() {
       var buf = new Buffer(4);
       buf.writeUInt32LE(1, 0);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readUInt32LE().should.equal(1);
     });
 
@@ -89,14 +97,14 @@ describe('BufferReader', function() {
       var buf = new Buffer(8);
       buf.fill(0);
       buf.writeUInt32BE(1, 4);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readUInt64BEBN().toNumber().should.equal(1);
     });
 
     it('should return 2^64', function() {
       var buf = new Buffer(8);
       buf.fill(0xff);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readUInt64BEBN().toNumber().should.equal(Math.pow(2, 64));
     });
 
@@ -108,7 +116,7 @@ describe('BufferReader', function() {
       var buf = new Buffer(8);
       buf.fill(0);
       buf.writeUInt32LE(1, 0);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readUInt64LEBN().toNumber().should.equal(1);
     });
 
@@ -116,21 +124,21 @@ describe('BufferReader', function() {
       var buf = new Buffer(8);
       buf.fill(0);
       buf.writeUInt32LE(Math.pow(2, 30), 0);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readUInt64LEBN().toNumber().should.equal(Math.pow(2, 30));
     });
 
     it('should return 0', function() {
       var buf = new Buffer(8);
       buf.fill(0);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readUInt64LEBN().toNumber().should.equal(0);
     });
 
     it('should return 2^64', function() {
       var buf = new Buffer(8);
       buf.fill(0xff);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readUInt64LEBN().toNumber().should.equal(Math.pow(2, 64));
     });
 
@@ -140,26 +148,26 @@ describe('BufferReader', function() {
 
     it('should read a 1 byte varint', function() {
       var buf = new Buffer([50]);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readVarInt().should.equal(50);
     });
 
     it('should read a 3 byte varint', function() {
       var buf = new Buffer([253, 253, 0]);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readVarInt().should.equal(253);
     });
 
     it('should read a 5 byte varint', function() {
       var buf = new Buffer([254, 0, 0, 0, 0]);
       buf.writeUInt32LE(50000, 1);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readVarInt().should.equal(50000);
     });
 
     it('should throw an error on a 9 byte varint', function() {
       var buf = Buffer.concat([new Buffer([255]), new Buffer('ffffffffffffffff', 'hex')]);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       (function() {
         br.readVarInt();
       }).should.throw('number too large to retain precision - use readVarIntBN');
@@ -171,26 +179,26 @@ describe('BufferReader', function() {
 
     it('should read a 1 byte varint', function() {
       var buf = new Buffer([50]);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readVarIntBN().toNumber().should.equal(50);
     });
 
     it('should read a 3 byte varint', function() {
       var buf = new Buffer([253, 253, 0]);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readVarIntBN().toNumber().should.equal(253);
     });
 
     it('should read a 5 byte varint', function() {
       var buf = new Buffer([254, 0, 0, 0, 0]);
       buf.writeUInt32LE(50000, 1);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readVarIntBN().toNumber().should.equal(50000);
     });
 
     it('should read a 9 byte varint', function() {
       var buf = Buffer.concat([new Buffer([255]), new Buffer('ffffffffffffffff', 'hex')]);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.readVarIntBN().toNumber().should.equal(Math.pow(2, 64));
     });
 
@@ -200,7 +208,7 @@ describe('BufferReader', function() {
     
     it('should reverse this [0, 1]', function() {
       var buf = new Buffer([0, 1]);
-      var br = new BufferReader(buf);
+      var br = new BufferReader({buf: buf});
       br.reverse().read().toString('hex').should.equal('0100');
     });
 
diff --git a/test/test.bufferwriter.js b/test/test.bufferwriter.js
index 02a7377..7ac33e5 100644
--- a/test/test.bufferwriter.js
+++ b/test/test.bufferwriter.js
@@ -126,7 +126,7 @@ describe('BufferWriter', function() {
       var n = Math.pow(2, 53);
       n.should.equal(n + 1); //javascript number precision limit
       bw.writeVarInt(n);
-      var br = new BufferReader(bw.concat());
+      var br = new BufferReader({buf: bw.concat()});
       br.readVarIntBN().toNumber().should.equal(n);
     });