diff --git a/src/transaction_builder.js b/src/transaction_builder.js
index 776259c..e563c2e 100644
--- a/src/transaction_builder.js
+++ b/src/transaction_builder.js
@@ -648,7 +648,7 @@ TransactionBuilder.prototype.__build = function (allowIncomplete) {
 
   if (!allowIncomplete) {
     // do not rely on this, its merely a last resort
-    if (this.__overMaximumFees(tx.byteLength())) {
+    if (this.__overMaximumFees(tx.virtualSize())) {
       throw new Error('Transaction has absurd fees')
     }
   }