diff --git a/x/derivatives/keeper/positions.go b/x/derivatives/keeper/positions.go
index 42cb036dc..5ef22fba6 100644
--- a/x/derivatives/keeper/positions.go
+++ b/x/derivatives/keeper/positions.go
@@ -1,6 +1,7 @@
 package keeper
 
 import (
+	"encoding/binary"
 	"errors"
 	"strconv"
 	"time"
@@ -10,12 +11,15 @@ import (
 	"github.com/UnUniFi/chain/x/derivatives/types"
 )
 
-func (k Keeper) GetLastPositionId(ctx sdk.Context) string {
+func (k Keeper) GetLastPositionId(ctx sdk.Context) uint64 {
 	store := ctx.KVStore(k.storeKey)
 
 	bz := store.Get([]byte(types.KeyPrefixLastPositionId))
+	if bz == nil {
+		return 0
+	}
 
-	return string(bz)
+	return binary.BigEndian.Uint64(bz)
 }
 
 func (k Keeper) GetLastPosition(ctx sdk.Context) types.Position {
@@ -43,7 +47,7 @@ func (k Keeper) IncreaseLastPositionId(ctx sdk.Context) {
 		store.Set([]byte(types.KeyPrefixLastPositionId), types.GetPositionIdBytes(0))
 	}
 
-	lastPositionId := types.GetPositionIdFromString(k.GetLastPositionId(ctx))
+	lastPositionId := k.GetLastPositionId(ctx)
 	store.Set([]byte(types.KeyPrefixLastPositionId), types.GetPositionIdBytes(lastPositionId+1))
 }
 
@@ -142,16 +146,7 @@ func (k Keeper) DeletePosition(ctx sdk.Context, address sdk.AccAddress, id strin
 func (k Keeper) OpenPosition(ctx sdk.Context, msg *types.MsgOpenPosition) error {
 	// todo check sender amount for margin
 
-	lastPosition := k.GetLastPosition(ctx)
-
-	var positionId string
-	if lastPosition.Id == "" {
-		positionId = "0"
-	} else {
-		// increment position id
-		lastPositionId, _ := strconv.Atoi(lastPosition.Id)
-		positionId = strconv.Itoa(lastPositionId + 1)
-	}
+	newPositionId := strconv.FormatUint(k.GetLastPositionId(ctx)+1, 10)
 
 	if err := k.bankKeeper.SendCoinsFromAccountToModule(ctx, msg.Sender.AccAddress(), types.ModuleName, sdk.NewCoins(msg.Margin)); err != nil {
 		return err
@@ -166,9 +161,9 @@ func (k Keeper) OpenPosition(ctx sdk.Context, msg *types.MsgOpenPosition) error
 	var position *types.Position
 	switch positionInstance := positionInstance.(type) {
 	case *types.PerpetualFuturesPositionInstance:
-		position, err = k.OpenPerpetualFuturesPosition(ctx, positionId, msg.Sender, msg.Margin, msg.Market, *positionInstance)
+		position, err = k.OpenPerpetualFuturesPosition(ctx, newPositionId, msg.Sender, msg.Margin, msg.Market, *positionInstance)
 	case *types.PerpetualOptionsPositionInstance:
-		position, err = k.OpenPerpetualOptionsPosition(ctx, positionId, msg.Sender, msg.Margin, msg.Market, *positionInstance)
+		position, err = k.OpenPerpetualOptionsPosition(ctx, newPositionId, msg.Sender, msg.Margin, msg.Market, *positionInstance)
 	default:
 		panic("")
 	}
diff --git a/x/derivatives/types/keys.go b/x/derivatives/types/keys.go
index 0a0d229cc..4a3bc26a3 100644
--- a/x/derivatives/types/keys.go
+++ b/x/derivatives/types/keys.go
@@ -66,6 +66,11 @@ func GetPositionIdFromString(idStr string) uint64 {
 	return GetPositionIdFromBytes([]byte(idStr))
 }
 
+func GetPositionIdByteFromString(idStr string) []byte {
+	intPosId, _ := strconv.Atoi(idStr)
+	return GetPositionIdBytes(uint64(intPosId))
+}
+
 func GetBlockTimestampBytes(timestamp int64) (timestampBz []byte) {
 	timestampBz = make([]byte, 8)
 	binary.BigEndian.PutUint64(timestampBz, uint64(timestamp))
@@ -93,7 +98,7 @@ func AssetDepositKeyPrefix(denom string) []byte {
 }
 
 func PositionWithIdKeyPrefix(posId string) []byte {
-	return append([]byte(KeyPrefixPosition), []byte(posId)...)
+	return append([]byte(KeyPrefixPosition), GetPositionIdByteFromString(posId)...)
 }
 
 func AddressPositionKeyPrefix(sender sdk.AccAddress) []byte {
@@ -101,7 +106,7 @@ func AddressPositionKeyPrefix(sender sdk.AccAddress) []byte {
 }
 
 func AddressPositionWithIdKeyPrefix(sender sdk.AccAddress, posId string) []byte {
-	return append(AddressPositionKeyPrefix(sender), []byte(posId)...)
+	return append(AddressPositionKeyPrefix(sender), GetPositionIdByteFromString(posId)...)
 }
 
 func DenomNetPositionPerpetualFuturesKeyPrefix(denom string, quoteDenom string) []byte {