diff --git a/consensus/oasys/snapshot.go b/consensus/oasys/snapshot.go
index 261937bc9..9fdf5ecf5 100644
--- a/consensus/oasys/snapshot.go
+++ b/consensus/oasys/snapshot.go
@@ -27,18 +27,40 @@ type Snapshot struct {
 	Number      uint64                            `json:"number"`                // Block number where the snapshot was created
 	Hash        common.Hash                       `json:"hash"`                  // Block hash where the snapshot was created
 	Validators  map[common.Address]*ValidatorInfo `json:"validators"`            // Set of authorized validators and stakes at this moment
-	Attestation *types.VoteData                   `json:"attestation:omitempty"` // Attestation for fast finality, but `Source` used as `Finalized`
+	Attestation *types.VoteData                   `json:"attestation,omitempty"` // Attestation for fast finality, but `Source` used as `Finalized`
 
 	Environment *params.EnvironmentValue `json:"environment"`
 }
 
 type ValidatorInfo struct {
 	// The index is determined by the sorted order of the validator owner address
-	Stake       *big.Int           `json:"stake:omitempty"`        // The stake amount
-	Index       int                `json:"index:omitempty"`        // The index should offset by 1
+	Stake       *big.Int           `json:"stake,omitempty"`        // The stake amount
+	Index       int                `json:"index,omitempty"`        // The index should offset by 1
 	VoteAddress types.BLSPublicKey `json:"vote_address,omitempty"` // The vote address
 }
 
+// Note: This code can be removed after each validators has been upgraded to v1.6.0.
+func (info *ValidatorInfo) UnmarshalJSON(b []byte) error {
+	// v1.5.0 or earlier
+	bigint := new(big.Int)
+	if err := json.Unmarshal(b, bigint); err == nil {
+		info.Stake = bigint
+		return nil
+	}
+
+	// v1.6.0 or later
+	type Alias ValidatorInfo
+	alias := new(Alias)
+	if err := json.Unmarshal(b, alias); err != nil {
+		return err
+	}
+
+	info.Stake = alias.Stake
+	info.Index = alias.Index
+	info.VoteAddress = alias.VoteAddress
+	return nil
+}
+
 // validatorsAscending implements the sort interface to allow sorting a list of addresses
 type validatorsAscending []common.Address
 
diff --git a/consensus/oasys/snapshot_test.go b/consensus/oasys/snapshot_test.go
new file mode 100644
index 000000000..c6d793e92
--- /dev/null
+++ b/consensus/oasys/snapshot_test.go
@@ -0,0 +1,44 @@
+package oasys
+
+import (
+	"encoding/json"
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/stretchr/testify/require"
+)
+
+func TestUnmarshalValidatorInfo(t *testing.T) {
+	jsonbody := []byte(`[
+		1,
+		{
+			"stake": 2,
+			"index": 3,
+			"vote_address": "0x000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000004"
+		}
+	]`)
+
+	expects := []*ValidatorInfo{
+		&ValidatorInfo{
+			Stake:       big.NewInt(1),
+			Index:       0,
+			VoteAddress: types.BLSPublicKey{},
+		},
+		&ValidatorInfo{
+			Stake: big.NewInt(2),
+			Index: 3,
+			VoteAddress: types.BLSPublicKey([]byte{
+				0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+				0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+				0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+				0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x4,
+			}),
+		},
+	}
+
+	var actuals []*ValidatorInfo
+	err := json.Unmarshal(jsonbody, &actuals)
+	require.NoError(t, err)
+	require.Equal(t, expects, actuals)
+}
diff --git a/core/types/vote.go b/core/types/vote.go
index 75f8166b3..81fe4c794 100644
--- a/core/types/vote.go
+++ b/core/types/vote.go
@@ -3,12 +3,14 @@ package types
 import (
 	"bytes"
 	"math/big"
+	"reflect"
 	"sync/atomic"
 
 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/v5/crypto/bls"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
 )
 
 const (
@@ -18,6 +20,10 @@ const (
 	MaxAttestationExtraLength = 256
 )
 
+var (
+	blsPublicKeyT = reflect.TypeOf(BLSPublicKey{})
+)
+
 type BLSPublicKey [BLSPublicKeyLength]byte
 type BLSSignature [BLSSignatureLength]byte
 type ValidatorsBitSet uint64
@@ -71,7 +77,19 @@ func (v *VoteEnvelope) calcVoteHash() common.Hash {
 	return rlpHash(vote)
 }
 
-func (b BLSPublicKey) Bytes() []byte { return b[:] }
+func (b BLSPublicKey) Bytes() []byte  { return b[:] }
+func (b BLSPublicKey) String() string { return hexutil.Encode(b[:]) }
+
+// MarshalText gets implements encoding.TextMarshaler. Since BLSPublicKey is stored as JSON in the
+// consensus engine's snapshot db, it is converted to a hex-string to improve readability and reduce size.
+func (b BLSPublicKey) MarshalText() ([]byte, error) {
+	return hexutil.Bytes(b[:]).MarshalText()
+}
+
+// UnmarshalJSON decodes the input as a string with 0x prefix
+func (b *BLSPublicKey) UnmarshalJSON(input []byte) error {
+	return hexutil.UnmarshalFixedJSON(blsPublicKeyT, input, b[:])
+}
 
 // Verify vote using BLS.
 func (vote *VoteEnvelope) Verify() error {