diff --git a/x/perp/v2/integration/action/dnr.go b/x/perp/v2/integration/action/dnr.go
index 464ea66a4..eb2c38035 100644
--- a/x/perp/v2/integration/action/dnr.go
+++ b/x/perp/v2/integration/action/dnr.go
@@ -203,7 +203,7 @@ type setCustomDiscountAction struct {
 	user   sdk.AccAddress
 }
 
-func (s setCustomDiscountAction) Do(app *app.NibiruApp, ctx sdk.Context) (outCtx sdk.Context, err error, isMandatory bool) {
+func (s *setCustomDiscountAction) Do(app *app.NibiruApp, ctx sdk.Context) (outCtx sdk.Context, err error, isMandatory bool) {
 	app.PerpKeeperV2.TraderDiscounts.Insert(ctx, collections.Join(s.user, s.volume), s.fee)
 	return ctx, nil, true
 }
diff --git a/x/perp/v2/keeper/dnr.go b/x/perp/v2/keeper/dnr.go
index 9a6103fb1..cb34a6838 100644
--- a/x/perp/v2/keeper/dnr.go
+++ b/x/perp/v2/keeper/dnr.go
@@ -1,6 +1,9 @@
 package keeper
 
 import (
+	"log"
+	"math/big"
+
 	"cosmossdk.io/math"
 	"github.com/NibiruChain/collections"
 	"github.com/NibiruChain/nibiru/x/common/asset"
@@ -48,20 +51,26 @@ func (i intValueEncoder) Name() string {
 type intKeyEncoder struct{}
 
 func (intKeyEncoder) Encode(key math.Int) []byte {
-	b, err := key.Marshal()
-	if err != nil {
-		panic(err)
+	i := key.BigInt()
+	if i.Sign() < 0 {
+		log.Panicf("cannot encode negative math.Int")
+	}
+	if i == nil {
+		log.Panicf("cannot encode nil key")
 	}
-	return b
+
+	be := i.Bytes()
+	padded := make([]byte, math.MaxBitLen)
+	copy(padded[math.MaxBitLen-len(be):], be)
+	return padded
 }
 
 func (intKeyEncoder) Decode(b []byte) (int, math.Int) {
-	i := math.Int{}
-	err := i.Unmarshal(b)
-	if err != nil {
-		panic(err)
+	if len(b) != math.MaxBitLen {
+		panic("invalid key length")
 	}
-	return len(b), i
+	i := new(big.Int).SetBytes(b)
+	return math.MaxBitLen, math.NewIntFromBigInt(i)
 }
 
 func (intKeyEncoder) Stringify(key math.Int) string { return key.String() }
diff --git a/x/perp/v2/keeper/dnr_test.go b/x/perp/v2/keeper/dnr_test.go
index 17f258a1e..bfa3f4fc4 100644
--- a/x/perp/v2/keeper/dnr_test.go
+++ b/x/perp/v2/keeper/dnr_test.go
@@ -106,7 +106,7 @@ func TestDiscount(t *testing.T) {
 
 	exchangeFee := sdk.MustNewDecFromStr("0.0010")           // 0.1%, default fee taken from CreateCustomMarketAction
 	globalFeeDiscount := sdk.MustNewDecFromStr("0.0005")     // 0.05%
-	fauxGlobalFeeDiscount := sdk.MustNewDecFromStr("0.0004") // 0.05%
+	fauxGlobalFeeDiscount := sdk.MustNewDecFromStr("0.0006") // 0.06%
 	customFeeDiscount := sdk.MustNewDecFromStr("0.0002")     // 0.02%
 	fauxCustomFeeDiscount := sdk.MustNewDecFromStr("0.0003") // 0.03%
 
@@ -150,10 +150,11 @@ func TestDiscount(t *testing.T) {
 				SetGlobalDiscount(globalFeeDiscount, sdk.NewInt(100_000)),
 				SetCustomDiscount(alice, fauxCustomFeeDiscount, sdk.NewInt(50_000)),
 				SetCustomDiscount(alice, customFeeDiscount, sdk.NewInt(100_000)),
-				SetPreviousEpochUserVolume(alice, sdk.NewInt(10_000)),
-			).Then(
-			MarketOrderFeeIs(exchangeFee, alice, pairBtcNusd, types.Direction_LONG, sdk.NewInt(10_000), sdk.OneDec(), sdk.ZeroDec()),
-		),
+				SetPreviousEpochUserVolume(alice, sdk.NewInt(10_000)), // lower than 50_000
+			).
+			Then(
+				MarketOrderFeeIs(exchangeFee, alice, pairBtcNusd, types.Direction_LONG, sdk.NewInt(10_000), sdk.OneDec(), sdk.ZeroDec()),
+			),
 		TC("user has past epoch volume: custom discount applies").
 			Given(
 				DnREpochIs(2),
@@ -195,7 +196,6 @@ func TestDiscount(t *testing.T) {
 			When(
 				SetGlobalDiscount(sdk.MustNewDecFromStr("0.0004"), sdk.NewInt(50_000)),
 				SetGlobalDiscount(globalFeeDiscount, sdk.NewInt(100_000)),
-				SetCustomDiscount(alice, sdk.MustNewDecFromStr("0.0003"), sdk.NewInt(50_000)),
 				SetPreviousEpochUserVolume(alice, sdk.NewInt(100_000)),
 			).
 			Then(