diff --git a/lib/block/block.js b/lib/block/block.js
index e127797..1b067b8 100644
--- a/lib/block/block.js
+++ b/lib/block/block.js
@@ -43,18 +43,7 @@ Block._from = function _from(arg) {
   } else if (JSUtil.isValidJSON(arg)) {
     info = Block._fromJSON(arg);
   } else if (_.isObject(arg)) {
-    info = {
-      /**
-       * @name Block#header
-       * @type {BlockHeader}
-       */
-      header: arg.header,
-      /**
-       * @name Block#transactions
-       * @type {Transaction[]}
-       */
-      transactions: arg.transactions
-    };
+    info = Block._fromObject(arg);
   } else {
     throw new TypeError('Unrecognized argument for Block');
   }
@@ -62,27 +51,35 @@ Block._from = function _from(arg) {
 };
 
 /**
- * @param {String|Object} - A JSON string or object
+ * @param {String} - A JSON string
  * @returns {Object} - An object representing block data
  * @private
  */
 Block._fromJSON = function _fromJSON(data) {
-  if (JSUtil.isValidJSON(data)) {
-    data = JSON.parse(data);
-  }
+  $.checkArgument(JSUtil.isValidJSON(data), 'data must be valid JSON');
+  data = JSON.parse(data);
+  return Block._fromObject(data);
+};
+
+/**
+ * @param {Object} - A plain javascript object
+ * @returns {Object} - An object representing block data
+ * @private
+ */
+Block._fromObject = function _fromObject(data) {
   var transactions = [];
   data.transactions.forEach(function(data) {
     transactions.push(Transaction().fromJSON(data));
   });
   var info = {
-    header: BlockHeader.fromJSON(data.header),
+    header: BlockHeader.fromObject(data.header),
     transactions: transactions
   };
   return info;
 };
 
 /**
- * @param {String|Object} - A JSON string or object
+ * @param {String} - A JSON string
  * @returns {Block} - An instance of block
  */
 Block.fromJSON = function fromJSON(json) {
@@ -90,6 +87,15 @@ Block.fromJSON = function fromJSON(json) {
   return new Block(info);
 };
 
+/**
+ * @param {Object} - A plain javascript object
+ * @returns {Block} - An instance of block
+ */
+Block.fromObject = function fromObject(obj) {
+  var info = Block._fromObject(obj);
+  return new Block(info);
+};
+
 /**
  * @param {BufferReader} - Block data
  * @returns {Object} - An object representing the block data
diff --git a/lib/block/blockheader.js b/lib/block/blockheader.js
index 01f2e81..c3280e3 100644
--- a/lib/block/blockheader.js
+++ b/lib/block/blockheader.js
@@ -7,6 +7,7 @@ var BufferReader = require('../encoding/bufferreader');
 var BufferWriter = require('../encoding/bufferwriter');
 var Hash = require('../crypto/hash');
 var JSUtil = require('../util/js');
+var $ = require('../util/preconditions');
 
 /**
  * Instantiate a BlockHeader from a Buffer, JSON object, or Object with
@@ -37,14 +38,7 @@ BlockHeader._from = function _from(arg) {
   } else if (JSUtil.isValidJSON(arg)) {
     info = BlockHeader._fromJSON(arg);
   } else if (_.isObject(arg)) {
-    info = {
-      version: arg.version,
-      prevHash: arg.prevHash,
-      merkleRoot: arg.merkleRoot,
-      time: arg.time,
-      bits: arg.bits,
-      nonce: arg.nonce
-    };
+    info = BlockHeader._fromObject(arg);
   } else {
     throw new TypeError('Unrecognized argument for BlockHeader');
   }
@@ -52,18 +46,35 @@ BlockHeader._from = function _from(arg) {
 };
 
 /**
- * @param {String|Object} - A JSON string or object
+ * @param {String} - A JSON string
  * @returns {Object} - An object representing block header data
  * @private
  */
 BlockHeader._fromJSON = function _fromJSON(data) {
-  if (JSUtil.isValidJSON(data)) {
-    data = JSON.parse(data);
+  $.checkArgument(JSUtil.isValidJSON(data), 'data must be a valid JSON string');
+  data = JSON.parse(data);
+  return BlockHeader._fromObject(data);
+};
+
+/**
+ * @param {Object} - A JSON string
+ * @returns {Object} - An object representing block header data
+ * @private
+ */
+BlockHeader._fromObject = function _fromObject(data) {
+  $.checkArgument(data, 'data is required');
+  var prevHash = data.prevHash;
+  var merkleRoot = data.merkleRoot;
+  if (_.isString(data.prevHash)) {
+    prevHash = BufferUtil.reverse(new Buffer(data.prevHash, 'hex'));
+  }
+  if (_.isString(data.merkleRoot)) {
+    merkleRoot = BufferUtil.reverse(new Buffer(data.merkleRoot, 'hex'));
   }
   var info = {
     version: data.version,
-    prevHash: new Buffer(data.prevHash, 'hex'),
-    merkleRoot: new Buffer(data.merkleRoot, 'hex'),
+    prevHash: prevHash,
+    merkleRoot: merkleRoot,
     time: data.time,
     timestamp: data.time,
     bits: data.bits,
@@ -73,7 +84,7 @@ BlockHeader._fromJSON = function _fromJSON(data) {
 };
 
 /**
- * @param {String|Object} - A JSON string or object
+ * @param {String} - A JSON string or object
  * @returns {BlockHeader} - An instance of block header
  */
 BlockHeader.fromJSON = function fromJSON(json) {
@@ -81,6 +92,15 @@ BlockHeader.fromJSON = function fromJSON(json) {
   return new BlockHeader(info);
 };
 
+/**
+ * @param {Object} - A plain javascript object
+ * @returns {BlockHeader} - An instance of block header
+ */
+BlockHeader.fromObject = function fromObject(obj) {
+  var info = BlockHeader._fromObject(obj);
+  return new BlockHeader(info);
+};
+
 /**
  * @param {Binary} - Raw block binary data or buffer
  * @returns {BlockHeader} - An instance of block header
@@ -144,8 +164,8 @@ BlockHeader.fromBufferReader = function fromBufferReader(br) {
 BlockHeader.prototype.toObject = function toObject() {
   return {
     version: this.version,
-    prevHash: this.prevHash.toString('hex'),
-    merkleRoot: this.merkleRoot.toString('hex'),
+    prevHash: BufferUtil.reverse(this.prevHash).toString('hex'),
+    merkleRoot: BufferUtil.reverse(this.merkleRoot).toString('hex'),
     time: this.time,
     bits: this.bits,
     nonce: this.nonce
@@ -216,8 +236,8 @@ var idProperty = {
   writeable: false,
   enumerable: true,
   /**
-  * @returns {string} - The big endian hash buffer of the header
-  */
+   * @returns {string} - The big endian hash buffer of the header
+   */
   get: function() {
     if (!this._id) {
       this._id = BufferReader(this._getHash()).readReverse().toString('hex');
diff --git a/lib/transaction/transaction.js b/lib/transaction/transaction.js
index 09ccc1a..3b6a7f4 100644
--- a/lib/transaction/transaction.js
+++ b/lib/transaction/transaction.js
@@ -313,6 +313,7 @@ Transaction.prototype.toObject = function toObject() {
     obj.changeIndex = this._changeIndex;
   }
   if (!_.isUndefined(this._fee)) {
+    console.log(this._fee);
     obj.fee = this._fee;
   }
   return obj;
@@ -320,6 +321,9 @@ Transaction.prototype.toObject = function toObject() {
 
 Transaction.prototype.fromObject = function(transaction) {
   var self = this;
+  if (transaction instanceof Transaction) {
+    transaction = transaction.toObject();
+  }
   _.each(transaction.inputs, function(input) {
     if (!input.output || !input.output.script) {
       self.uncheckedAddInput(new Input(input));
@@ -595,6 +599,7 @@ Transaction.prototype.hasAllUtxoInfo = function() {
  * @return {Transaction} this, for chaining
  */
 Transaction.prototype.fee = function(amount) {
+  $.checkArgument(_.isNumber(amount), 'amount must be a number');
   this._fee = amount;
   this._updateChangeOutput();
   return this;
diff --git a/test/block.js b/test/block.js
index f6f0685..cdf1758 100644
--- a/test/block.js
+++ b/test/block.js
@@ -167,7 +167,7 @@ describe('Block', function() {
 
   });
 
-  describe.only('#toObject', function() {
+  describe('#toObject', function() {
 
     it('should recover a block from genesis block buffer', function() {
       var block = Block.fromBuffer(blockOneBuf);
@@ -199,6 +199,13 @@ describe('Block', function() {
       });
     });
 
+    it('roundtrips correctly', function() {
+      var block = Block.fromBuffer(blockOneBuf);
+      var obj = block.toObject();
+      var block2 = Block.fromObject(obj);
+      block2.toObject().should.deep.equal(block.toObject());
+    });
+
   });
 
   describe('#_getHash', function() {