diff --git a/lib/bcoin/block.js b/lib/bcoin/block.js
index 7b612b12..05c50a29 100644
--- a/lib/bcoin/block.js
+++ b/lib/bcoin/block.js
@@ -71,24 +71,24 @@ Block.prototype.getRaw = function getRaw() {
   return raw;
 };
 
-Block.prototype.getVirtualSize = function getVirtualSize() {
+Block.prototype.getVirtualSize = function getVirtualSize(force) {
   var size, witnessSize, base;
 
-  size = this.getSize();
-  witnessSize = this.getWitnessSize();
+  size = this.getSize(force);
+  witnessSize = this.getWitnessSize(force);
   base = size - witnessSize;
 
   return (base * 4 + witnessSize + 3) / 4 | 0;
 };
 
-Block.prototype.getSize = function getSize() {
-  if (this._size == null)
+Block.prototype.getSize = function getSize(force) {
+  if (force || this._size === 0)
     this.getRaw();
   return this._size;
 };
 
-Block.prototype.getWitnessSize = function getWitnessSize() {
-  if (this._witnessSize == null)
+Block.prototype.getWitnessSize = function getWitnessSize(force) {
+  if (force || this._size === 0)
     this.getRaw();
   return this._witnessSize;
 };