diff --git a/common/bytes.go b/common/bytes.go
index 8520b330db..c82e616241 100644
--- a/common/bytes.go
+++ b/common/bytes.go
@@ -31,7 +31,7 @@ func ToHex(b []byte) string {
 	return "0x" + hex
 }
 
-// creates a array of hex-string based on []byte
+// ToHexArray creates a array of hex-string based on []byte
 func ToHexArray(b [][]byte) []string {
 	r := make([]string, len(b))
 	for i := range b {
diff --git a/core/state/statedb.go b/core/state/statedb.go
index 6d229f748a..b1bb53ed04 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -26,6 +26,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/rlp"
@@ -257,28 +258,20 @@ func (self *StateDB) GetState(addr common.Address, hash common.Hash) common.Hash
 	return common.Hash{}
 }
 
-// MerkleProof
-type ProofList [][]byte
-
-func (n *ProofList) Put(key []byte, value []byte) error {
-	*n = append(*n, value)
-	return nil
-}
-
 // GetProof returns the MerkleProof for a given Account
-func (self *StateDB) GetProof(a common.Address) ([][]byte, error) {
-	var proof ProofList
+func (self *StateDB) GetProof(a common.Address) (vm.ProofList, error) {
+	var proof vm.ProofList
 	err := self.trie.Prove(crypto.Keccak256(a.Bytes()), 0, &proof)
 	return proof, err
 }
 
 // GetProof returns the StorageProof for given key
-func (self *StateDB) GetStorageProof(a common.Address, key common.Hash) ([][]byte, error) {
+func (self *StateDB) GetStorageProof(a common.Address, key common.Hash) (vm.ProofList, error) {
+	var proof vm.ProofList
 	trie := self.StorageTrie(a)
 	if trie == nil {
-		return [][]byte{}, errors.New("storage trie for requested address does not exist")
+		return proof, errors.New("storage trie for requested address does not exist")
 	}
-	var proof ProofList
 	err := trie.Prove(crypto.Keccak256(key.Bytes()), 0, &proof)
 	return proof, err
 }
diff --git a/core/vm/interface.go b/core/vm/interface.go
index fe2f3d713e..1ae98cf7a2 100644
--- a/core/vm/interface.go
+++ b/core/vm/interface.go
@@ -35,8 +35,8 @@ type StateDB interface {
 	SetNonce(common.Address, uint64)
 
 	GetCodeHash(common.Address) common.Hash
-	GetProof(common.Address) ([][]byte, error)
-	GetStorageProof(common.Address, common.Hash) ([][]byte, error)
+	GetProof(common.Address) (ProofList, error)
+	GetStorageProof(common.Address, common.Hash) (ProofList, error)
 	GetCode(common.Address) []byte
 	SetCode(common.Address, []byte)
 	GetCodeSize(common.Address) int
@@ -80,3 +80,11 @@ type CallContext interface {
 	// Create a new contract
 	Create(env *EVM, me ContractRef, data []byte, gas, value *big.Int) ([]byte, common.Address, error)
 }
+
+// MerkleProof
+type ProofList [][]byte
+
+func (n *ProofList) Put(key []byte, value []byte) error {
+	*n = append(*n, value)
+	return nil
+}