diff --git a/lib/bcoin/block.js b/lib/bcoin/block.js
index ebdc2ddb..5f8b2aa2 100644
--- a/lib/bcoin/block.js
+++ b/lib/bcoin/block.js
@@ -50,6 +50,7 @@ function Block(data) {
   this.txs = data.txs || [];
   this._cbHeight = null;
   this._commitmentHash = null;
+  this._raw = null;
 
   for (i = 0; i < this.txs.length; i++) {
     tx = this.txs[i];
@@ -78,6 +79,8 @@ Block.prototype.render = function render() {
  */
 
 Block.prototype.renderNormal = function renderNormal() {
+  if (!this.hasWitness())
+    return this.getRaw();
   return bcoin.protocol.framer.block(this);
 };
 
@@ -87,6 +90,8 @@ Block.prototype.renderNormal = function renderNormal() {
  */
 
 Block.prototype.renderWitness = function renderWitness() {
+  if (this.hasWitness())
+    return this.getRaw();
   return bcoin.protocol.framer.witnessBlock(this);
 };
 
@@ -99,6 +104,12 @@ Block.prototype.renderWitness = function renderWitness() {
 Block.prototype.getRaw = function getRaw() {
   var raw;
 
+  if (this._raw) {
+    assert(this._size > 0);
+    assert(this._witnessSize >= 0);
+    return this._raw;
+  }
+
   if (this.hasWitness())
     raw = bcoin.protocol.framer.witnessBlock(this);
   else
@@ -107,6 +118,7 @@ Block.prototype.getRaw = function getRaw() {
   if (!this.mutable) {
     this._size = raw.length;
     this._witnessSize = raw._witnessSize;
+    this._raw = raw;
   }
 
   return raw;
@@ -127,6 +139,14 @@ Block.prototype.getSizes = function getSizes() {
     };
   }
 
+  if (!this.mutable) {
+    this.getRaw();
+    return {
+      size: this._size,
+      witnessSize: this._witnessSize
+    };
+  }
+
   sizes = bcoin.protocol.framer.block.sizes(this);
 
   if (!this.mutable) {
@@ -184,7 +204,12 @@ Block.prototype.getBaseSize = function getBaseSize() {
  */
 
 Block.prototype.hasWitness = function hasWitness() {
-  for (var i = 0; i < this.txs.length; i++) {
+  var i;
+
+  if (this._witnessSize > 0)
+    return true;
+
+  for (i = 0; i < this.txs.length; i++) {
     if (this.txs[i].hasWitness())
       return true;
   }
diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index d4089fcc..a04505c0 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -369,6 +369,9 @@ TX.prototype.getBaseSize = function getBaseSize() {
 TX.prototype.hasWitness = function hasWitness() {
   var i;
 
+  if (this._witnessSize > 0)
+    return true;
+
   for (i = 0; i < this.inputs.length; i++) {
     if (this.inputs[i].witness.items.length > 0)
       return true;