diff --git a/lib/block.js b/lib/block.js
index 2b2d2de..a9c807e 100644
--- a/lib/block.js
+++ b/lib/block.js
@@ -244,22 +244,32 @@ Block.prototype.validMerkleRoot = function validMerkleRoot() {
 /**
  * @returns {Buffer} - The little endian hash buffer of the header
  */
-Block.prototype.hash = function hash() {
-  return this.blockheader.hash();
+Block.prototype._getHash = function() {
+  return this.blockheader._getHash();
 };
 
-/**
- * @returns {Buffer} - The big endian hash buffer of the header
- */
-Block.prototype.id = function id() {
-  return this.blockheader.id();
+var idProperty = {
+  configurable: false,
+  writeable: false,
+  /**
+   * @returns {string} - The big endian hash buffer of the header
+   */
+  get: function() {
+    if (!this._id) {
+      this._id = this.blockheader.id;
+    }
+    return this._id;
+  },
+  set: _.noop
 };
+Object.defineProperty(Block.prototype, 'id', idProperty);
+Object.defineProperty(Block.prototype, 'hash', idProperty);
 
 /**
  * @returns {String} - A string formated for the console
  */
 Block.prototype.inspect = function inspect() {
-  return '<Block ' + this.id().toString('hex') + '>';
+  return '<Block ' + this.id + '>';
 };
 
 Block.Values = {
diff --git a/lib/blockheader.js b/lib/blockheader.js
index 175e529..9531609 100644
--- a/lib/blockheader.js
+++ b/lib/blockheader.js
@@ -183,17 +183,27 @@ BlockHeader.prototype.getTargetDifficulty = function getTargetDifficulty(info) {
 /**
  * @returns {Buffer} - The little endian hash buffer of the header
  */
-BlockHeader.prototype.hash = function hash() {
+BlockHeader.prototype._getHash = function hash() {
   var buf = this.toBuffer();
   return Hash.sha256sha256(buf);
 };
 
-/**
- * @returns {Buffer} - The big endian hash buffer of the header
- */
-BlockHeader.prototype.id = function id() {
-  return BufferReader(this.hash()).reverse().read();
+var idProperty = {
+  configurable: false,
+  writeable: false,
+  /**
+  * @returns {string} - The big endian hash buffer of the header
+  */
+  get: function() {
+    if (!this._id) {
+      this._id = BufferReader(this._getHash()).readReverse().toString('hex');
+    }
+    return this._id;
+  },
+  set: _.noop
 };
+Object.defineProperty(BlockHeader.prototype, 'id', idProperty);
+Object.defineProperty(BlockHeader.prototype, 'hash', idProperty);
 
 /**
  * @returns {Boolean} - If timestamp is not too far in the future
@@ -210,9 +220,9 @@ BlockHeader.prototype.validTimestamp = function validTimestamp() {
  * @returns {Boolean} - If the proof-of-work hash satisfies the target difficulty
  */
 BlockHeader.prototype.validProofOfWork = function validProofOfWork() {
-  var hash = this.id().toString('hex');
-  var pow = new BN(hash, 'hex');
+  var pow = new BN(this.id, 'hex');
   var target = this.getTargetDifficulty();
+
   if (pow.cmp(target) > 0) {
     return false;
   }
@@ -223,7 +233,7 @@ BlockHeader.prototype.validProofOfWork = function validProofOfWork() {
  * @returns {String} - A string formated for the console
  */
 BlockHeader.prototype.inspect = function inspect() {
-  return '<BlockHeader ' + this.id().toString('hex') + '>';
+  return '<BlockHeader ' + this.id + '>';
 };
 
 BlockHeader.Constants = {
diff --git a/test/block.js b/test/block.js
index 61d8cc3..a72f541 100644
--- a/test/block.js
+++ b/test/block.js
@@ -154,21 +154,24 @@ describe('Block', function() {
 
   });
 
-  describe('#hash', function() {
+  describe('#_getHash', function() {
 
     it('should return the correct hash of the genesis block', function() {
       var block = Block.fromBuffer(genesisbuf);
       var blockhash = new Buffer(Array.apply([], new Buffer(genesisidhex, 'hex')).reverse());
-      block.hash().toString('hex').should.equal(blockhash.toString('hex'));
+      block._getHash().toString('hex').should.equal(blockhash.toString('hex'));
     });
-
   });
 
   describe('#id', function() {
 
     it('should return the correct id of the genesis block', function() {
       var block = Block.fromBuffer(genesisbuf);
-      block.id().toString('hex').should.equal(genesisidhex);
+      block.id.should.equal(genesisidhex);
+    });
+    it('"hash" should be the same as "id"', function() {
+      var block = Block.fromBuffer(genesisbuf);
+      block.id.should.equal(block.hash);
     });
 
   });
diff --git a/test/blockheader.js b/test/blockheader.js
index b07a6d2..dc0127c 100644
--- a/test/blockheader.js
+++ b/test/blockheader.js
@@ -199,15 +199,15 @@ describe('BlockHeader', function() {
 
   describe('#validProofOfWork', function() {
 
-    var x = BlockHeader.fromRawBlock(dataRawBlockBuffer);
-
     it('should validate proof-of-work as true', function() {
+      var x = BlockHeader.fromRawBlock(dataRawBlockBuffer);
       var valid = x.validProofOfWork(x);
       valid.should.equal(true);
 
     });
 
     it('should validate proof of work as false because incorrect proof of work', function() {
+      var x = BlockHeader.fromRawBlock(dataRawBlockBuffer);
       var nonce = x.nonce;
       x.nonce = 0;
       var valid = x.validProofOfWork(x);