diff --git a/lib/primitives/block.js b/lib/primitives/block.js
index c4370bf9..22514404 100644
--- a/lib/primitives/block.js
+++ b/lib/primitives/block.js
@@ -37,8 +37,6 @@ function Block(options) {
 
   this.txs = [];
 
-  this._cbHeight = null;
-
   this._raw = null;
   this._size = -1;
   this._witness = -1;
@@ -253,7 +251,7 @@ Block.prototype.addTX = function addTX(tx) {
 
 /**
  * Test the block's transaction vector against a hash.
- * @param {Hash|TX} hash
+ * @param {Hash} hash
  * @returns {Boolean}
  */
 
@@ -263,7 +261,7 @@ Block.prototype.hasTX = function hasTX(hash) {
 
 /**
  * Find the index of a transaction in the block.
- * @param {Hash|TX} hash
+ * @param {Hash} hash
  * @returns {Number} index (-1 if not present).
  */
 
@@ -506,20 +504,15 @@ Block.prototype.getCoinbaseHeight = function getCoinbaseHeight() {
   if (this.version < 2)
     return -1;
 
-  if (this._cbHeight != null)
-    return this._cbHeight;
+  if (this.txs.length === 0)
+    return -1;
 
   coinbase = this.txs[0];
 
-  if (!coinbase || coinbase.inputs.length === 0)
+  if (coinbase.inputs.length === 0)
     return -1;
 
-  height = coinbase.inputs[0].script.getCoinbaseHeight();
-
-  if (!this.mutable)
-    this._cbHeight = height;
-
-  return height;
+  return coinbase.inputs[0].script.getCoinbaseHeight();
 };
 
 /**
@@ -528,7 +521,7 @@ Block.prototype.getCoinbaseHeight = function getCoinbaseHeight() {
  */
 
 Block.prototype.getClaimed = function getClaimed() {
-  assert(this.txs[0]);
+  assert(this.txs.length > 0);
   assert(this.txs[0].isCoinbase());
   return this.txs[0].getOutputValue();
 };
diff --git a/lib/primitives/memblock.js b/lib/primitives/memblock.js
index 6c685f2e..9b589197 100644
--- a/lib/primitives/memblock.js
+++ b/lib/primitives/memblock.js
@@ -13,6 +13,7 @@ var Block = require('./block');
 var Script = require('../script/script');
 var Headers = require('./headers');
 var BufferReader = require('../utils/reader');
+var DUMMY = new Buffer(0);
 
 /**
  * A block object which is essentially a "placeholder"
@@ -39,8 +40,7 @@ function MemBlock() {
   if (!(this instanceof MemBlock))
     return new MemBlock();
 
-  this._cbHeight = -1;
-  this._raw = null;
+  this._raw = DUMMY;
 }
 
 util.inherits(MemBlock, AbstractBlock);
@@ -84,13 +84,57 @@ MemBlock.prototype.verifyBody = function verifyBody(ret) {
 };
 
 /**
- * Retrieve the coinbase height from the coinbase input script (already
- * extracted in actuality).
+ * Retrieve the coinbase height
+ * from the coinbase input script.
  * @returns {Number} height (-1 if not present).
  */
 
 MemBlock.prototype.getCoinbaseHeight = function getCoinbaseHeight() {
-  return this._cbHeight;
+  if (this.version < 2)
+    return -1;
+
+  try {
+    return this.parseCoinbaseHeight();
+  } catch (e) {
+    return -1;
+  }
+};
+
+/**
+ * Parse the coinbase height
+ * from the coinbase input script.
+ * @private
+ * @returns {Number} height (-1 if not present).
+ */
+
+MemBlock.prototype.parseCoinbaseHeight = function parseCoinbaseHeight() {
+  var br = new BufferReader(this._raw, true);
+  var count, script;
+
+  br.seek(80);
+
+  count = br.readVarint();
+
+  if (count === 0)
+    return -1;
+
+  br.seek(4);
+
+  count = br.readVarint();
+
+  if (count === 0) {
+    if (br.readU8() !== 0)
+      count = br.readVarint();
+  }
+
+  if (count === 0)
+    return -1;
+
+  br.seek(36);
+
+  script = br.readVarBytes();
+
+  return Script.getCoinbaseHeight(script);
 };
 
 /**
@@ -101,30 +145,9 @@ MemBlock.prototype.getCoinbaseHeight = function getCoinbaseHeight() {
 
 MemBlock.prototype.fromRaw = function fromRaw(data) {
   var br = new BufferReader(data, true);
-  var height = -1;
-  var count, script;
 
   this.parseAbbr(br);
 
-  count = br.readVarint();
-
-  if (this.version > 1 && count > 0) {
-    br.seek(4);
-    count = br.readVarint();
-
-    if (count === 0) {
-      if (br.readU8() !== 0)
-        count = br.readVarint();
-    }
-
-    if (count > 0) {
-      br.seek(36);
-      script = br.readVarBytes();
-      height = Script.getCoinbaseHeight(script);
-    }
-  }
-
-  this._cbHeight = height;
   this._raw = br.data;
 
   return this;
@@ -167,10 +190,10 @@ MemBlock.prototype.toNormal = function toNormal() {
 
 MemBlock.prototype.toBlock = function toBlock() {
   var block = Block.fromRaw(this._raw);
+
   block._hash = this._hash;
   block._hhash = this._hhash;
-  block._cbHeight = this._cbHeight;
-  this._raw = null;
+
   return block;
 };