diff --git a/packages/asset-swapper/src/quote_consumers/utils.ts b/packages/asset-swapper/src/quote_consumers/utils.ts
index 9f5d40b871..67b2677acf 100644
--- a/packages/asset-swapper/src/quote_consumers/utils.ts
+++ b/packages/asset-swapper/src/quote_consumers/utils.ts
@@ -1,12 +1,9 @@
 import { BigNumber } from '@0x/utils';
 import * as _ from 'lodash';
 
-import { constants } from '../constants';
 import { MarketOperation, SwapQuote } from '../types';
 import { ERC20BridgeSource } from '../utils/market_operation_utils/types';
 
-const { ZERO_AMOUNT } = constants;
-
 /**
  * Compute the mminimum buy token amount for market operations by inferring
  * the slippage from the orders in a quote. We cannot rely on
@@ -17,23 +14,20 @@ export function getSwapMinBuyAmount(quote: SwapQuote): BigNumber {
     if (quote.type === MarketOperation.Buy || quote.isTwoHop) {
         return quote.worstCaseQuoteInfo.makerAssetAmount;
     }
-    // Infer the allowed maker asset slippage from the orders.
-    const totalOrderMakerAssetAmount = BigNumber.sum(...quote.orders.map(o => o.fillableMakerAssetAmount));
-    // tslint:disable: prefer-conditional-expression
-    let totalFillMakerAssetAmount = ZERO_AMOUNT;
+    let slipRatio = new BigNumber(1);
+    // Infer the allowed maker asset slippage from any non-native order.
     for (const o of quote.orders) {
         if (o.fills.length === 0 || o.fills[0].source === ERC20BridgeSource.Native) {
-            // No slippage on natuve orders.
-            totalFillMakerAssetAmount = totalFillMakerAssetAmount.plus(o.fillableMakerAssetAmount);
-        } else {
-            totalFillMakerAssetAmount = totalFillMakerAssetAmount.plus(BigNumber.sum(...o.fills.map(f => f.output)));
+            // No slippage on native orders.
+            continue;
         }
+        const totalFillMakerAssetAmount = BigNumber.sum(...o.fills.map(f => f.output));
+        slipRatio = o.fillableMakerAssetAmount.div(totalFillMakerAssetAmount);
+        break;
     }
-    // tslint:enable: prefer-conditional-expression
-    if (totalOrderMakerAssetAmount.eq(totalFillMakerAssetAmount)) {
+    if (slipRatio.gte(1)) {
         // No slippage allowed across all orders.
         return quote.bestCaseQuoteInfo.makerAssetAmount;
     }
-    const slipRatio = totalOrderMakerAssetAmount.div(totalFillMakerAssetAmount);
     return quote.bestCaseQuoteInfo.makerAssetAmount.times(slipRatio).integerValue(BigNumber.ROUND_DOWN);
 }