diff --git a/lib/primitives/mtx.js b/lib/primitives/mtx.js
index 718bf336..470581ee 100644
--- a/lib/primitives/mtx.js
+++ b/lib/primitives/mtx.js
@@ -1228,7 +1228,7 @@ MTX.prototype.selectCoins = function selectCoins(coins, options) {
  * @param {Amount} fee
  */
 
-MTX.prototype.subtractFee = function subtractFee(index, fee) {
+MTX.prototype.subtractIndex = function subtractIndex(index, fee) {
   assert(typeof index === 'number');
   assert(typeof fee === 'number');