diff --git a/ts/client/src/accounts/serum3.ts b/ts/client/src/accounts/serum3.ts
index 0b1e14ec0..f888bc4fd 100644
--- a/ts/client/src/accounts/serum3.ts
+++ b/ts/client/src/accounts/serum3.ts
@@ -81,7 +81,7 @@ export class Serum3Market {
       this.name === 'USDT/USDC'
         ? { maker: -0.5, taker: 1 }
         : { maker: -2, taker: 4 };
-    return taker ? ratesBps.maker * 0.0001 : ratesBps.taker * 0.0001;
+    return taker ? ratesBps.taker * 0.0001 : ratesBps.maker * 0.0001;
   }
 
   /**
diff --git a/ts/client/src/client.ts b/ts/client/src/client.ts
index 0c1346185..c0866732a 100644
--- a/ts/client/src/client.ts
+++ b/ts/client/src/client.ts
@@ -1612,12 +1612,12 @@ export class MangoClient {
     const limitPrice = serum3MarketExternal.priceNumberToLots(price);
     const maxBaseQuantity = serum3MarketExternal.baseSizeNumberToLots(size);
     const isTaker = orderType !== Serum3OrderType.postOnly;
-    const maxQuoteQuantity = new BN(
+    const maxQuoteQuantity = new BN(Math.ceil(
       serum3MarketExternal.decoded.quoteLotSize.toNumber() *
         (1 + Math.max(serum3Market.getFeeRates(isTaker), 0)) *
         serum3MarketExternal.baseSizeNumberToLots(size).toNumber() *
         serum3MarketExternal.priceNumberToLots(price).toNumber(),
-    );
+    ));
 
     const payerTokenIndex = ((): TokenIndex => {
       if (side == Serum3Side.bid) {