diff --git a/lib/bill-math.js b/lib/bill-math.js
index 589573e5..fa0b8db8 100644
--- a/lib/bill-math.js
+++ b/lib/bill-math.js
@@ -1,6 +1,7 @@
 const _ = require('lodash/fp')
 const sumService = require('@haensl/subset-sum')
 
+const BN = require('./bn')
 const logger = require('./logger')
 const cc = require('./coin-change')
 
@@ -152,9 +153,9 @@ const solutionToOriginalUnits = (solution, units) => {
 
 function makeChange(outCassettes, amount) {
   const ss_solution = getSolution_old(outCassettes, amount, BILL_LIST_MODES.VALUE_ROUND_ROBIN)
-  const cc_solution = cc.solve(cc.model(outCassettes), amount.toNumber())
+  const cc_solution = getSolution(outCassettes, amount)
 
-  if (!!ss_solution === !!cc_solution) {
+  if (!!ss_solution !== !!cc_solution) {
     logger.error(new Error(`subset-sum and coin-change don't agree on solvability -- subset-sum:${!!ss_solution} coin-change:${!!cc_solution}`))
     return solutionToOriginalUnits(ss_solution, outCassettes)
   }