diff --git a/pkg/core/native/validators_count.go b/pkg/core/native/validators_count.go
index be551bfdb..d3b0feccf 100644
--- a/pkg/core/native/validators_count.go
+++ b/pkg/core/native/validators_count.go
@@ -1,6 +1,7 @@
 package native
 
 import (
+	"errors"
 	"math/big"
 
 	"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
@@ -41,6 +42,7 @@ func (vc *ValidatorsCount) Bytes() []byte {
 
 // EncodeBinary implements io.Serializable interface.
 func (vc *ValidatorsCount) EncodeBinary(w *io.BinWriter) {
+	w.WriteVarUint(uint64(MaxValidatorsVoted))
 	for i := range vc {
 		w.WriteVarBytes(bigint.ToBytes(&vc[i]))
 	}
@@ -48,7 +50,12 @@ func (vc *ValidatorsCount) EncodeBinary(w *io.BinWriter) {
 
 // DecodeBinary implements io.Serializable interface.
 func (vc *ValidatorsCount) DecodeBinary(r *io.BinReader) {
-	for i := range vc {
+	count := r.ReadVarUint()
+	if count < 0 || count > MaxValidatorsVoted {
+		r.Err = errors.New("invalid validators count")
+		return
+	}
+	for i := 0; i < int(count); i++ {
 		buf := r.ReadVarBytes()
 		if r.Err != nil {
 			return
diff --git a/pkg/core/state/native_state.go b/pkg/core/state/native_state.go
index 9c8b3d915..d551c6711 100644
--- a/pkg/core/state/native_state.go
+++ b/pkg/core/state/native_state.go
@@ -4,8 +4,8 @@ import (
 	"math/big"
 
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
-	"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
 	"github.com/nspcc-dev/neo-go/pkg/io"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 )
 
 // NEP5BalanceState represents balance state of a NEP5-token.
@@ -44,18 +44,27 @@ func (s *NEP5BalanceState) Bytes() []byte {
 	return w.Bytes()
 }
 
+func (s *NEP5BalanceState) toStackItem() stackitem.Item {
+	return stackitem.NewStruct([]stackitem.Item{stackitem.NewBigInteger(&s.Balance)})
+}
+
+func (s *NEP5BalanceState) fromStackItem(item stackitem.Item) {
+	s.Balance = *item.(*stackitem.Struct).Value().([]stackitem.Item)[0].Value().(*big.Int)
+}
+
 // EncodeBinary implements io.Serializable interface.
 func (s *NEP5BalanceState) EncodeBinary(w *io.BinWriter) {
-	w.WriteVarBytes(bigint.ToBytes(&s.Balance))
+	si := s.toStackItem()
+	stackitem.EncodeBinaryStackItem(si, w)
 }
 
 // DecodeBinary implements io.Serializable interface.
 func (s *NEP5BalanceState) DecodeBinary(r *io.BinReader) {
-	buf := r.ReadVarBytes()
+	si := stackitem.DecodeBinaryStackItem(r)
 	if r.Err != nil {
 		return
 	}
-	s.Balance = *bigint.FromBytes(buf)
+	s.fromStackItem(si)
 }
 
 // NEOBalanceStateFromBytes converts serialized NEOBalanceState to structure.
@@ -85,14 +94,37 @@ func (s *NEOBalanceState) Bytes() []byte {
 
 // EncodeBinary implements io.Serializable interface.
 func (s *NEOBalanceState) EncodeBinary(w *io.BinWriter) {
-	s.NEP5BalanceState.EncodeBinary(w)
-	w.WriteU32LE(s.BalanceHeight)
-	w.WriteArray(s.Votes)
+	si := s.toStackItem()
+	stackitem.EncodeBinaryStackItem(si, w)
 }
 
 // DecodeBinary implements io.Serializable interface.
 func (s *NEOBalanceState) DecodeBinary(r *io.BinReader) {
-	s.NEP5BalanceState.DecodeBinary(r)
-	s.BalanceHeight = r.ReadU32LE()
-	r.ReadArray(&s.Votes)
+	si := stackitem.DecodeBinaryStackItem(r)
+	if r.Err != nil {
+		return
+	}
+	s.fromStackItem(si)
+}
+
+func (s *NEOBalanceState) toStackItem() stackitem.Item {
+	result := s.NEP5BalanceState.toStackItem().(*stackitem.Struct)
+	result.Append(stackitem.NewBigInteger(big.NewInt(int64(s.BalanceHeight))))
+	votes := make([]stackitem.Item, len(s.Votes))
+	for i, v := range s.Votes {
+		votes[i] = stackitem.NewByteArray(v.Bytes())
+	}
+	result.Append(stackitem.NewArray(votes))
+	return result
+}
+
+func (s *NEOBalanceState) fromStackItem(item stackitem.Item) {
+	structItem := item.Value().([]stackitem.Item)
+	s.Balance = *structItem[0].Value().(*big.Int)
+	s.BalanceHeight = uint32(structItem[1].Value().(*big.Int).Int64())
+	votes := structItem[2].Value().([]stackitem.Item)
+	s.Votes = make([]*keys.PublicKey, len(votes))
+	for i, v := range votes {
+		s.Votes[i].DecodeBytes(v.Value().([]byte))
+	}
 }