diff --git a/account/account.go b/account/account.go
index 03b9d3eb..081dc106 100644
--- a/account/account.go
+++ b/account/account.go
@@ -12,13 +12,13 @@ import (
 // Signable is an interface for all signable things.
 // It typically removes signatures before serializing.
 type Signable interface {
-	WriteSignBytes(w io.Writer, n *int64, err *error)
+	WriteSignBytes(chainID string, w io.Writer, n *int64, err *error)
 }
 
 // SignBytes is a convenience method for getting the bytes to sign of a Signable.
-func SignBytes(o Signable) []byte {
+func SignBytes(chainID string, o Signable) []byte {
 	buf, n, err := new(bytes.Buffer), new(int64), new(error)
-	o.WriteSignBytes(buf, n, err)
+	o.WriteSignBytes(chainID, buf, n, err)
 	if *err != nil {
 		panic(err)
 	}
@@ -26,8 +26,8 @@ func SignBytes(o Signable) []byte {
 }
 
 // HashSignBytes is a convenience method for getting the hash of the bytes of a signable
-func HashSignBytes(o Signable) []byte {
-	return merkle.HashFromBinary(SignBytes(o))
+func HashSignBytes(chainID string, o Signable) []byte {
+	return merkle.HashFromBinary(SignBytes(chainID, o))
 }
 
 //-----------------------------------------------------------------------------
diff --git a/account/priv_account.go b/account/priv_account.go
index ccd702b1..ad4fc650 100644
--- a/account/priv_account.go
+++ b/account/priv_account.go
@@ -52,8 +52,8 @@ func GenPrivAccountFromKey(privKeyBytes [64]byte) *PrivAccount {
 	}
 }
 
-func (privAccount *PrivAccount) Sign(o Signable) Signature {
-	return privAccount.PrivKey.Sign(SignBytes(o))
+func (privAccount *PrivAccount) Sign(chainID string, o Signable) Signature {
+	return privAccount.PrivKey.Sign(SignBytes(chainID, o))
 }
 
 func (privAccount *PrivAccount) String() string {
diff --git a/blockchain/reactor.go b/blockchain/reactor.go
index e48da66f..322ed5c3 100644
--- a/blockchain/reactor.go
+++ b/blockchain/reactor.go
@@ -232,7 +232,7 @@ FOR_LOOP:
 				firstPartsHeader := firstParts.Header()
 				// Finally, verify the first block using the second's validation.
 				err := bcR.state.BondedValidators.VerifyValidation(
-					first.Hash(), firstPartsHeader, first.Height, second.Validation)
+					bcR.state.ChainID, first.Hash(), firstPartsHeader, first.Height, second.Validation)
 				if err != nil {
 					log.Debug("error in validation", "error", err)
 					bcR.pool.RedoRequest(first.Height)
diff --git a/cmd/tendermint/gen_tx.go b/cmd/tendermint/gen_tx.go
index 687339be..d499fad8 100644
--- a/cmd/tendermint/gen_tx.go
+++ b/cmd/tendermint/gen_tx.go
@@ -110,6 +110,6 @@ func gen_tx() {
 	}
 
 	// Sign
-	tx.Inputs[0].Signature = srcPrivKey.Sign(account.SignBytes(tx))
+	tx.Inputs[0].Signature = srcPrivKey.Sign(account.SignBytes(config.GetString("chain_id"), tx))
 	fmt.Printf("Signed tx: %X\n", binary.BinaryBytes(tx))
 }
diff --git a/consensus/pol.go b/consensus/pol.go
index 433a6992..7314eb48 100644
--- a/consensus/pol.go
+++ b/consensus/pol.go
@@ -38,7 +38,7 @@ func (pol *POL) Verify(valSet *sm.ValidatorSet) error {
 	}
 
 	talliedVotingPower := uint64(0)
-	prevoteDoc := account.SignBytes(&types.Vote{
+	prevoteDoc := account.SignBytes(config.GetString("chain_id"), &types.Vote{
 		Height: pol.Height, Round: pol.Round, Type: types.VoteTypePrevote,
 		BlockHash:  pol.BlockHash,
 		BlockParts: pol.BlockParts,
@@ -55,7 +55,7 @@ func (pol *POL) Verify(valSet *sm.ValidatorSet) error {
 
 		// Commit vote?
 		if vote.Round < pol.Round {
-			voteDoc = account.SignBytes(&types.Vote{
+			voteDoc = account.SignBytes(config.GetString("chain_id"), &types.Vote{
 				Height: pol.Height, Round: vote.Round, Type: types.VoteTypeCommit,
 				BlockHash:  pol.BlockHash,
 				BlockParts: pol.BlockParts,
diff --git a/consensus/pol_test.go b/consensus/pol_test.go
index db55bd5d..5b56969d 100644
--- a/consensus/pol_test.go
+++ b/consensus/pol_test.go
@@ -3,8 +3,8 @@ package consensus
 import (
 	"github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/common"
-	sm "github.com/tendermint/tendermint/state"
 	_ "github.com/tendermint/tendermint/config/tendermint_test"
+	sm "github.com/tendermint/tendermint/state"
 	"github.com/tendermint/tendermint/types"
 
 	"bytes"
@@ -18,7 +18,7 @@ import (
 // Returns the POLVoteSignature pointer, so you can modify it afterwards.
 func signAddPOLVoteSignature(val *sm.PrivValidator, valSet *sm.ValidatorSet, vote *types.Vote, pol *POL) *POLVoteSignature {
 	vote = vote.Copy()
-	err := val.SignVote(vote)
+	err := val.SignVote(config.GetString("chain_id"), vote)
 	if err != nil {
 		panic(err)
 	}
diff --git a/consensus/state.go b/consensus/state.go
index 0f75f531..de7b5fd2 100644
--- a/consensus/state.go
+++ b/consensus/state.go
@@ -16,7 +16,7 @@ Consensus State Machine Overview:
 * The NewHeight is a transition period after the height is incremented,
   where the node still receives late commits before potentially proposing.
   The height should be incremented because a block had been
-  "committed by the chain_id", and clients should see that
+  "committed by the network", and clients should see that
   reflected as a new height.
 
                             +-------------------------------------+
@@ -536,7 +536,7 @@ func (cs *ConsensusState) updateToState(state *sm.State, contiguous bool) {
 			Address: cs.privValidator.Address,
 			Height:  cs.Height,
 		}
-		err := cs.privValidator.SignRebondTx(rebondTx)
+		err := cs.privValidator.SignRebondTx(cs.state.ChainID, rebondTx)
 		if err == nil {
 			err := cs.mempoolReactor.BroadcastTx(rebondTx)
 			if err != nil {
@@ -656,7 +656,7 @@ func (cs *ConsensusState) RunActionPropose(height uint, round uint) {
 		txs := cs.mempoolReactor.Mempool.GetProposalTxs()
 		block = &types.Block{
 			Header: &types.Header{
-				ChainID:        config.GetString("chain_id"),
+				ChainID:        cs.state.ChainID,
 				Height:         cs.Height,
 				Time:           time.Now(),
 				Fees:           0, // TODO fees
@@ -688,7 +688,7 @@ func (cs *ConsensusState) RunActionPropose(height uint, round uint) {
 
 	// Make proposal
 	proposal := NewProposal(cs.Height, cs.Round, blockParts.Header(), polParts.Header())
-	err := cs.privValidator.SignProposal(proposal)
+	err := cs.privValidator.SignProposal(cs.state.ChainID, proposal)
 	if err == nil {
 		log.Info("Signed and set proposal", "height", cs.Height, "round", cs.Round, "proposal", proposal)
 		log.Debug(Fmt("Signed and set proposal block: %v", block))
@@ -939,7 +939,7 @@ func (cs *ConsensusState) SetProposal(proposal *Proposal) error {
 	}
 
 	// Verify signature
-	if !cs.Validators.Proposer().PubKey.VerifyBytes(account.SignBytes(proposal), proposal.Signature) {
+	if !cs.Validators.Proposer().PubKey.VerifyBytes(account.SignBytes(cs.state.ChainID, proposal), proposal.Signature) {
 		return ErrInvalidProposalSignature
 	}
 
@@ -1111,7 +1111,7 @@ func (cs *ConsensusState) signAddVote(type_ byte, hash []byte, header types.Part
 		BlockHash:  hash,
 		BlockParts: header,
 	}
-	err := cs.privValidator.SignVote(vote)
+	err := cs.privValidator.SignVote(cs.state.ChainID, vote)
 	if err == nil {
 		log.Info("Signed and added vote", "height", cs.Height, "round", cs.Round, "vote", vote)
 		cs.addVote(cs.privValidator.Address, vote)
diff --git a/consensus/state_test.go b/consensus/state_test.go
index 8ab22039..af25ae01 100644
--- a/consensus/state_test.go
+++ b/consensus/state_test.go
@@ -16,7 +16,7 @@ func TestSetupRound(t *testing.T) {
 	voteTypes := []byte{types.VoteTypePrevote, types.VoteTypePrecommit, types.VoteTypeCommit}
 	for _, voteType := range voteTypes {
 		vote := &types.Vote{Height: 1, Round: 0, Type: voteType} // nil vote
-		err := val0.SignVote(vote)
+		err := val0.SignVote(cs.state.ChainID, vote)
 		if err != nil {
 			t.Error("Error signing vote: %v", err)
 		}
@@ -124,7 +124,7 @@ func TestRunActionPrecommitCommitFinalize(t *testing.T) {
 			BlockHash:  cs.ProposalBlock.Hash(),
 			BlockParts: cs.ProposalBlockParts.Header(),
 		}
-		err := privValidators[i].SignVote(vote)
+		err := privValidators[i].SignVote(cs.state.ChainID, vote)
 		if err != nil {
 			t.Error("Error signing vote: %v", err)
 		}
@@ -154,7 +154,7 @@ func TestRunActionPrecommitCommitFinalize(t *testing.T) {
 			BlockHash:  cs.ProposalBlock.Hash(),
 			BlockParts: cs.ProposalBlockParts.Header(),
 		}
-		err := privValidators[i].SignVote(vote)
+		err := privValidators[i].SignVote(cs.state.ChainID, vote)
 		if err != nil {
 			t.Error("Error signing vote: %v", err)
 		}
@@ -192,7 +192,7 @@ func TestRunActionPrecommitCommitFinalize(t *testing.T) {
 			BlockHash:  cs.ProposalBlock.Hash(),
 			BlockParts: cs.ProposalBlockParts.Header(),
 		}
-		err := privValidators[i].SignVote(vote)
+		err := privValidators[i].SignVote(cs.state.ChainID, vote)
 		if err != nil {
 			t.Error("Error signing vote: %v", err)
 		}
diff --git a/consensus/types/proposal.go b/consensus/types/proposal.go
index 642fa59f..a306f032 100644
--- a/consensus/types/proposal.go
+++ b/consensus/types/proposal.go
@@ -38,9 +38,9 @@ func (p *Proposal) String() string {
 		p.BlockParts, p.POLParts, p.Signature)
 }
 
-func (p *Proposal) WriteSignBytes(w io.Writer, n *int64, err *error) {
+func (p *Proposal) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
 	// We hex encode the chain_id name so we don't deal with escaping issues.
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, config.GetString("chain_id"))), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, chainID)), w, n, err)
 	binary.WriteTo([]byte(`,"proposal":{"block_parts":`), w, n, err)
 	p.BlockParts.WriteSignBytes(w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"height":%v,"pol_parts":`, p.Height)), w, n, err)
diff --git a/consensus/types/proposal_test.go b/consensus/types/proposal_test.go
index cef57faf..fa8f37be 100644
--- a/consensus/types/proposal_test.go
+++ b/consensus/types/proposal_test.go
@@ -17,7 +17,7 @@ func TestProposalSignable(t *testing.T) {
 		POLParts:   types.PartSetHeader{222, []byte("polparts")},
 		Signature:  nil,
 	}
-	signBytes := account.SignBytes(proposal)
+	signBytes := account.SignBytes(config.GetString("chain_id"), proposal)
 	signStr := string(signBytes)
 	expected := Fmt(`{"chain_id":"%X","proposal":{"block_parts":{"hash":"626C6F636B7061727473","total":111},"height":12345,"pol_parts":{"hash":"706F6C7061727473","total":222},"round":23456}}`,
 		config.GetString("chain_id"))
diff --git a/consensus/vote_set.go b/consensus/vote_set.go
index 21e98661..ca2f44eb 100644
--- a/consensus/vote_set.go
+++ b/consensus/vote_set.go
@@ -93,7 +93,7 @@ func (voteSet *VoteSet) Add(address []byte, vote *types.Vote) (bool, uint, error
 	}
 
 	// Check signature.
-	if !val.PubKey.VerifyBytes(account.SignBytes(vote), vote.Signature) {
+	if !val.PubKey.VerifyBytes(account.SignBytes(config.GetString("chain_id"), vote), vote.Signature) {
 		// Bad signature.
 		return false, 0, types.ErrVoteInvalidSignature
 	}
diff --git a/consensus/vote_set_test.go b/consensus/vote_set_test.go
index 2c94d682..212fcf66 100644
--- a/consensus/vote_set_test.go
+++ b/consensus/vote_set_test.go
@@ -5,8 +5,8 @@ import (
 
 	. "github.com/tendermint/tendermint/common"
 	. "github.com/tendermint/tendermint/common/test"
-	sm "github.com/tendermint/tendermint/state"
 	_ "github.com/tendermint/tendermint/config/tendermint_test"
+	sm "github.com/tendermint/tendermint/state"
 	"github.com/tendermint/tendermint/types"
 
 	"testing"
@@ -50,7 +50,7 @@ func withBlockParts(vote *types.Vote, blockParts types.PartSetHeader) *types.Vot
 }
 
 func signAddVote(privVal *sm.PrivValidator, vote *types.Vote, voteSet *VoteSet) (bool, error) {
-	privVal.SignVoteUnsafe(vote)
+	privVal.SignVoteUnsafe(config.GetString("chain_id"), vote)
 	added, _, err := voteSet.Add(privVal.Address, vote)
 	return added, err
 }
diff --git a/rpc/core/mempool.go b/rpc/core/mempool.go
index 4fa93560..e4ae7709 100644
--- a/rpc/core/mempool.go
+++ b/rpc/core/mempool.go
@@ -17,7 +17,7 @@ func BroadcastTx(tx types.Tx) (*ctypes.ResponseBroadcastTx, error) {
 		return nil, fmt.Errorf("Error broadcasting transaction: %v", err)
 	}
 
-	txHash := types.TxId(tx)
+	txHash := types.TxId(mempoolReactor.Mempool.GetState().ChainID, tx)
 	var createsContract uint8
 	var contractAddr []byte
 	// check if creates new contract
diff --git a/rpc/core/net.go b/rpc/core/net.go
index 842602a2..f74510e7 100644
--- a/rpc/core/net.go
+++ b/rpc/core/net.go
@@ -66,7 +66,8 @@ func NetInfo() (*ctypes.ResponseNetInfo, error) {
 func Genesis() (*string, error) {
 	b, err := ioutil.ReadFile(config.GetString("genesis_file"))
 	if err != nil {
-		return "", err
+		return nil, err
 	}
-	return &string(b), nil
+	ret := string(b)
+	return &ret, nil
 }
diff --git a/rpc/core/txs.go b/rpc/core/txs.go
index e0c40a55..07e14d94 100644
--- a/rpc/core/txs.go
+++ b/rpc/core/txs.go
@@ -91,27 +91,27 @@ func SignTx(tx types.Tx, privAccounts []*account.PrivAccount) (*ctypes.ResponseS
 		sendTx := tx.(*types.SendTx)
 		for i, input := range sendTx.Inputs {
 			input.PubKey = privAccounts[i].PubKey
-			input.Signature = privAccounts[i].Sign(sendTx)
+			input.Signature = privAccounts[i].Sign(config.GetString("chain_id"), sendTx)
 		}
 	case *types.CallTx:
 		callTx := tx.(*types.CallTx)
 		callTx.Input.PubKey = privAccounts[0].PubKey
-		callTx.Input.Signature = privAccounts[0].Sign(callTx)
+		callTx.Input.Signature = privAccounts[0].Sign(config.GetString("chain_id"), callTx)
 	case *types.BondTx:
 		bondTx := tx.(*types.BondTx)
 		// the first privaccount corresponds to the BondTx pub key.
 		// the rest to the inputs
-		bondTx.Signature = privAccounts[0].Sign(bondTx).(account.SignatureEd25519)
+		bondTx.Signature = privAccounts[0].Sign(config.GetString("chain_id"), bondTx).(account.SignatureEd25519)
 		for i, input := range bondTx.Inputs {
 			input.PubKey = privAccounts[i+1].PubKey
-			input.Signature = privAccounts[i+1].Sign(bondTx)
+			input.Signature = privAccounts[i+1].Sign(config.GetString("chain_id"), bondTx)
 		}
 	case *types.UnbondTx:
 		unbondTx := tx.(*types.UnbondTx)
-		unbondTx.Signature = privAccounts[0].Sign(unbondTx).(account.SignatureEd25519)
+		unbondTx.Signature = privAccounts[0].Sign(config.GetString("chain_id"), unbondTx).(account.SignatureEd25519)
 	case *types.RebondTx:
 		rebondTx := tx.(*types.RebondTx)
-		rebondTx.Signature = privAccounts[0].Sign(rebondTx).(account.SignatureEd25519)
+		rebondTx.Signature = privAccounts[0].Sign(config.GetString("chain_id"), rebondTx).(account.SignatureEd25519)
 	}
 	return &ctypes.ResponseSignTx{tx}, nil
 }
diff --git a/rpc/test/client_ws_test.go b/rpc/test/client_ws_test.go
index a5d0880c..5f94306b 100644
--- a/rpc/test/client_ws_test.go
+++ b/rpc/test/client_ws_test.go
@@ -193,6 +193,6 @@ func TestWSCallCall(t *testing.T) {
 	waitForEvent(t, con, eid1, true, func() {
 		tx := makeDefaultCallTx(t, wsTyp, contractAddr2, nil, amt, gasLim, fee)
 		broadcastTx(t, wsTyp, tx)
-		*txid = account.HashSignBytes(tx)
+		*txid = account.HashSignBytes(chainID, tx)
 	}, unmarshalValidateCallCall(user[0].Address, returnVal, txid))
 }
diff --git a/rpc/test/helpers.go b/rpc/test/helpers.go
index 8602c0bf..da05ccfd 100644
--- a/rpc/test/helpers.go
+++ b/rpc/test/helpers.go
@@ -32,6 +32,8 @@ var (
 	userPriv = "C453604BD6480D5538B4C6FD2E3E314B5BCE518D75ADE4DA3DA85AB8ADFD819606FBAC4E285285D1D91FCBC7E91C780ADA11516F67462340B3980CE2B94940E8"
 	user     = makeUsers(2)
 
+	chainID string
+
 	clients = map[string]cclient.Client{
 		"JSONRPC": cclient.NewClient(requestAddr, "JSONRPC"),
 		"HTTP":    cclient.NewClient(requestAddr, "HTTP"),
@@ -74,6 +76,8 @@ func newNode(ready chan struct{}) {
 
 // initialize config and create new node
 func init() {
+	chainID = config.GetString("chain_id")
+
 	// Save new priv_validator file.
 	priv := &state.PrivValidator{
 		Address: user[0].Address,
@@ -83,7 +87,7 @@ func init() {
 	priv.SetFile(config.GetString("priv_validator_file"))
 	priv.Save()
 
-	consensus.RoundDuration0 = 3 * time.Second
+	consensus.RoundDuration0 = 2 * time.Second
 	consensus.RoundDurationDelta = 1 * time.Second
 
 	// start a node
@@ -105,14 +109,14 @@ func makeDefaultSendTx(t *testing.T, typ string, addr []byte, amt uint64) *types
 
 func makeDefaultSendTxSigned(t *testing.T, typ string, addr []byte, amt uint64) *types.SendTx {
 	tx := makeDefaultSendTx(t, typ, addr, amt)
-	tx.SignInput(0, user[0])
+	tx.SignInput(chainID, 0, user[0])
 	return tx
 }
 
 func makeDefaultCallTx(t *testing.T, typ string, addr, code []byte, amt, gasLim, fee uint64) *types.CallTx {
 	nonce := getNonce(t, typ, user[0].Address)
 	tx := types.NewCallTxWithNonce(user[0].PubKey, addr, code, amt, gasLim, fee, nonce)
-	tx.Sign(user[0])
+	tx.Sign(chainID, user[0])
 	return tx
 }
 
@@ -214,7 +218,7 @@ func checkTx(t *testing.T, fromAddr []byte, priv *account.PrivAccount, tx *types
 		t.Fatal("Tx input addresses don't match!")
 	}
 
-	signBytes := account.SignBytes(tx)
+	signBytes := account.SignBytes(chainID, tx)
 	in := tx.Inputs[0] //(*types.SendTx).Inputs[0]
 
 	if err := in.ValidateBasic(); err != nil {
diff --git a/rpc/test/tests.go b/rpc/test/tests.go
index 7a172c2c..ca9221ea 100644
--- a/rpc/test/tests.go
+++ b/rpc/test/tests.go
@@ -15,9 +15,9 @@ func testStatus(t *testing.T, typ string) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if resp.ChainID != config.GetString("chain_id") {
+	if resp.ChainID != chainID {
 		t.Fatal(fmt.Errorf("ChainID mismatch: got %s expected %s",
-			resp.ChainID, config.Get("chain_id")))
+			resp.ChainID, chainID))
 	}
 }
 
@@ -57,9 +57,9 @@ func testSignedTx(t *testing.T, typ string) {
 func testOneSignTx(t *testing.T, typ string, addr []byte, amt uint64) {
 	tx := makeDefaultSendTx(t, typ, addr, amt)
 	tx2 := signTx(t, typ, tx, user[0])
-	tx2hash := account.HashSignBytes(tx2)
-	tx.SignInput(0, user[0])
-	txhash := account.HashSignBytes(tx)
+	tx2hash := account.HashSignBytes(chainID, tx2)
+	tx.SignInput(chainID, 0, user[0])
+	txhash := account.HashSignBytes(chainID, tx)
 	if bytes.Compare(txhash, tx2hash) != 0 {
 		t.Fatal("Got different signatures for signing via rpc vs tx_utils")
 	}
@@ -88,8 +88,8 @@ func testBroadcastTx(t *testing.T, typ string) {
 	tx2 := txs[mempoolCount-1].(*types.SendTx)
 	n, err := new(int64), new(error)
 	buf1, buf2 := new(bytes.Buffer), new(bytes.Buffer)
-	tx.WriteSignBytes(buf1, n, err)
-	tx2.WriteSignBytes(buf2, n, err)
+	tx.WriteSignBytes(chainID, buf1, n, err)
+	tx2.WriteSignBytes(chainID, buf2, n, err)
 	if bytes.Compare(buf1.Bytes(), buf2.Bytes()) != 0 {
 		t.Fatal("inconsistent hashes for mempool tx and sent tx")
 	}
diff --git a/state/execution.go b/state/execution.go
index 9b6c35be..e46a2150 100644
--- a/state/execution.go
+++ b/state/execution.go
@@ -33,7 +33,7 @@ func ExecBlock(s *State, block *types.Block, blockPartsHeader types.PartSetHeade
 // at an invalid state.  Copy the state before calling execBlock!
 func execBlock(s *State, block *types.Block, blockPartsHeader types.PartSetHeader) error {
 	// Basic block validation.
-	err := block.ValidateBasic(s.LastBlockHeight, s.LastBlockHash, s.LastBlockParts, s.LastBlockTime)
+	err := block.ValidateBasic(s.ChainID, s.LastBlockHeight, s.LastBlockHash, s.LastBlockParts, s.LastBlockTime)
 	if err != nil {
 		return err
 	}
@@ -61,7 +61,7 @@ func execBlock(s *State, block *types.Block, blockPartsHeader types.PartSetHeade
 					BlockHash:  block.LastBlockHash,
 					BlockParts: block.LastBlockParts,
 				}
-				if val.PubKey.VerifyBytes(account.SignBytes(vote), commit.Signature) {
+				if val.PubKey.VerifyBytes(account.SignBytes(s.ChainID, vote), commit.Signature) {
 					sumVotingPower += val.VotingPower
 					return false
 				} else {
@@ -305,7 +305,7 @@ func ExecTx(blockCache *BlockCache, tx_ types.Tx, runCall bool, evc events.Firea
 		if err != nil {
 			return err
 		}
-		signBytes := account.SignBytes(tx)
+		signBytes := account.SignBytes(_s.ChainID, tx)
 		inTotal, err := validateInputs(accounts, signBytes, tx.Inputs)
 		if err != nil {
 			return err
@@ -353,7 +353,7 @@ func ExecTx(blockCache *BlockCache, tx_ types.Tx, runCall bool, evc events.Firea
 			log.Debug(Fmt("Can't find pubkey for %X", tx.Input.Address))
 			return err
 		}
-		signBytes := account.SignBytes(tx)
+		signBytes := account.SignBytes(_s.ChainID, tx)
 		err := validateInput(inAcc, signBytes, tx.Input)
 		if err != nil {
 			log.Debug(Fmt("validateInput failed on %X:", tx.Input.Address))
@@ -433,7 +433,7 @@ func ExecTx(blockCache *BlockCache, tx_ types.Tx, runCall bool, evc events.Firea
 
 			txCache.UpdateAccount(caller) // because we adjusted by input above, and bumped nonce maybe.
 			txCache.UpdateAccount(callee) // because we adjusted by input above.
-			vmach := vm.NewVM(txCache, params, caller.Address, account.HashSignBytes(tx))
+			vmach := vm.NewVM(txCache, params, caller.Address, account.HashSignBytes(_s.ChainID, tx))
 			vmach.SetFireable(evc)
 			// NOTE: Call() transfers the value from caller to callee iff call succeeds.
 
@@ -490,7 +490,7 @@ func ExecTx(blockCache *BlockCache, tx_ types.Tx, runCall bool, evc events.Firea
 			return err
 		}
 
-		signBytes := account.SignBytes(tx)
+		signBytes := account.SignBytes(_s.ChainID, tx)
 		inTotal, err := validateInputs(accounts, signBytes, tx.Inputs)
 		if err != nil {
 			return err
@@ -548,7 +548,7 @@ func ExecTx(blockCache *BlockCache, tx_ types.Tx, runCall bool, evc events.Firea
 		}
 
 		// Verify the signature
-		signBytes := account.SignBytes(tx)
+		signBytes := account.SignBytes(_s.ChainID, tx)
 		if !val.PubKey.VerifyBytes(signBytes, tx.Signature) {
 			return types.ErrTxInvalidSignature
 		}
@@ -573,7 +573,7 @@ func ExecTx(blockCache *BlockCache, tx_ types.Tx, runCall bool, evc events.Firea
 		}
 
 		// Verify the signature
-		signBytes := account.SignBytes(tx)
+		signBytes := account.SignBytes(_s.ChainID, tx)
 		if !val.PubKey.VerifyBytes(signBytes, tx.Signature) {
 			return types.ErrTxInvalidSignature
 		}
@@ -599,8 +599,8 @@ func ExecTx(blockCache *BlockCache, tx_ types.Tx, runCall bool, evc events.Firea
 				return types.ErrTxInvalidAddress
 			}
 		}
-		voteASignBytes := account.SignBytes(&tx.VoteA)
-		voteBSignBytes := account.SignBytes(&tx.VoteB)
+		voteASignBytes := account.SignBytes(_s.ChainID, &tx.VoteA)
+		voteBSignBytes := account.SignBytes(_s.ChainID, &tx.VoteB)
 		if !accused.PubKey.VerifyBytes(voteASignBytes, tx.VoteA.Signature) ||
 			!accused.PubKey.VerifyBytes(voteBSignBytes, tx.VoteB.Signature) {
 			return types.ErrTxInvalidSignature
diff --git a/state/priv_validator.go b/state/priv_validator.go
index 607a789e..6ddfb3b4 100644
--- a/state/priv_validator.go
+++ b/state/priv_validator.go
@@ -109,7 +109,7 @@ func (privVal *PrivValidator) save() {
 }
 
 // TODO: test
-func (privVal *PrivValidator) SignVote(vote *types.Vote) error {
+func (privVal *PrivValidator) SignVote(chainID string, vote *types.Vote) error {
 	privVal.mtx.Lock()
 	defer privVal.mtx.Unlock()
 
@@ -140,15 +140,15 @@ func (privVal *PrivValidator) SignVote(vote *types.Vote) error {
 	privVal.save()
 
 	// Sign
-	privVal.SignVoteUnsafe(vote)
+	privVal.SignVoteUnsafe(chainID, vote)
 	return nil
 }
 
-func (privVal *PrivValidator) SignVoteUnsafe(vote *types.Vote) {
-	vote.Signature = privVal.PrivKey.Sign(account.SignBytes(vote)).(account.SignatureEd25519)
+func (privVal *PrivValidator) SignVoteUnsafe(chainID string, vote *types.Vote) {
+	vote.Signature = privVal.PrivKey.Sign(account.SignBytes(chainID, vote)).(account.SignatureEd25519)
 }
 
-func (privVal *PrivValidator) SignProposal(proposal *Proposal) error {
+func (privVal *PrivValidator) SignProposal(chainID string, proposal *Proposal) error {
 	privVal.mtx.Lock()
 	defer privVal.mtx.Unlock()
 	if privVal.LastHeight < proposal.Height ||
@@ -162,14 +162,14 @@ func (privVal *PrivValidator) SignProposal(proposal *Proposal) error {
 		privVal.save()
 
 		// Sign
-		proposal.Signature = privVal.PrivKey.Sign(account.SignBytes(proposal)).(account.SignatureEd25519)
+		proposal.Signature = privVal.PrivKey.Sign(account.SignBytes(chainID, proposal)).(account.SignatureEd25519)
 		return nil
 	} else {
 		return errors.New(fmt.Sprintf("Attempt of duplicate signing of proposal: Height %v, Round %v", proposal.Height, proposal.Round))
 	}
 }
 
-func (privVal *PrivValidator) SignRebondTx(rebondTx *types.RebondTx) error {
+func (privVal *PrivValidator) SignRebondTx(chainID string, rebondTx *types.RebondTx) error {
 	privVal.mtx.Lock()
 	defer privVal.mtx.Unlock()
 	if privVal.LastHeight < rebondTx.Height {
@@ -181,7 +181,7 @@ func (privVal *PrivValidator) SignRebondTx(rebondTx *types.RebondTx) error {
 		privVal.save()
 
 		// Sign
-		rebondTx.Signature = privVal.PrivKey.Sign(account.SignBytes(rebondTx)).(account.SignatureEd25519)
+		rebondTx.Signature = privVal.PrivKey.Sign(account.SignBytes(chainID, rebondTx)).(account.SignatureEd25519)
 		return nil
 	} else {
 		return errors.New(fmt.Sprintf("Attempt of duplicate signing of rebondTx: Height %v", rebondTx.Height))
diff --git a/state/state_test.go b/state/state_test.go
index 1885c8f1..a2fb2b78 100644
--- a/state/state_test.go
+++ b/state/state_test.go
@@ -65,7 +65,7 @@ func TestCopyState(t *testing.T) {
 func makeBlock(t *testing.T, state *State, commits []types.Commit, txs []types.Tx) *types.Block {
 	block := &types.Block{
 		Header: &types.Header{
-			ChainID:        "tendermint_test",
+			ChainID:        state.ChainID,
 			Height:         state.LastBlockHeight + 1,
 			Time:           state.LastBlockTime.Add(time.Minute),
 			Fees:           0,
@@ -191,7 +191,7 @@ func TestTxSequence(t *testing.T) {
 	for i := -1; i < 3; i++ {
 		sequence := acc0.Sequence + uint(i)
 		tx := makeSendTx(sequence)
-		tx.Inputs[0].Signature = privAccounts[0].Sign(tx)
+		tx.Inputs[0].Signature = privAccounts[0].Sign(state.ChainID, tx)
 		stateCopy := state.Copy()
 		err := execTxWithState(stateCopy, tx, true)
 		if i == 1 {
@@ -251,7 +251,7 @@ func TestTxs(t *testing.T) {
 			},
 		}
 
-		tx.Inputs[0].Signature = privAccounts[0].Sign(tx)
+		tx.Inputs[0].Signature = privAccounts[0].Sign(state.ChainID, tx)
 		err := execTxWithState(state, tx, true)
 		if err != nil {
 			t.Errorf("Got error in executing send transaction, %v", err)
@@ -288,8 +288,8 @@ func TestTxs(t *testing.T) {
 				},
 			},
 		}
-		tx.Signature = privAccounts[0].Sign(tx).(account.SignatureEd25519)
-		tx.Inputs[0].Signature = privAccounts[0].Sign(tx)
+		tx.Signature = privAccounts[0].Sign(state.ChainID, tx).(account.SignatureEd25519)
+		tx.Inputs[0].Signature = privAccounts[0].Sign(state.ChainID, tx)
 		err := execTxWithState(state, tx, true)
 		if err != nil {
 			t.Errorf("Got error in executing bond transaction, %v", err)
@@ -345,8 +345,8 @@ func TestAddValidator(t *testing.T) {
 			},
 		},
 	}
-	bondTx.Signature = acc0.Sign(bondTx).(account.SignatureEd25519)
-	bondTx.Inputs[0].Signature = acc0.Sign(bondTx)
+	bondTx.Signature = acc0.Sign(s0.ChainID, bondTx).(account.SignatureEd25519)
+	bondTx.Inputs[0].Signature = acc0.Sign(s0.ChainID, bondTx)
 
 	// Make complete block and blockParts
 	block0 := makeBlock(t, s0, nil, []types.Tx{bondTx})
@@ -380,7 +380,7 @@ func TestAddValidator(t *testing.T) {
 		BlockHash:  block0.Hash(),
 		BlockParts: block0Parts.Header(),
 	}
-	privValidators[0].SignVote(commit0)
+	privValidators[0].SignVote(s0.ChainID, commit0)
 
 	block1 := makeBlock(t, s0,
 		[]types.Commit{
diff --git a/state/test.go b/state/test.go
index efb425fb..8e0f3520 100644
--- a/state/test.go
+++ b/state/test.go
@@ -97,6 +97,7 @@ func RandGenesisState(numAccounts int, randBalance bool, minBalance uint64, numV
 	sort.Sort(PrivValidatorsByAddress(privValidators))
 	s0 := MakeGenesisState(db, &GenesisDoc{
 		GenesisTime: time.Now(),
+		ChainID:     "tendermint_test",
 		Accounts:    accounts,
 		Validators:  validators,
 	})
diff --git a/state/validator_set.go b/state/validator_set.go
index 2d247313..a7cede7c 100644
--- a/state/validator_set.go
+++ b/state/validator_set.go
@@ -201,7 +201,7 @@ func (valSet *ValidatorSet) Iterate(fn func(index uint, val *Validator) bool) {
 }
 
 // Verify that +2/3 of the set had signed the given signBytes
-func (valSet *ValidatorSet) VerifyValidation(hash []byte, parts types.PartSetHeader, height uint, v *types.Validation) error {
+func (valSet *ValidatorSet) VerifyValidation(chainID string, hash []byte, parts types.PartSetHeader, height uint, v *types.Validation) error {
 	if valSet.Size() != uint(len(v.Commits)) {
 		return errors.New(Fmt("Invalid validation -- wrong set size: %v vs %v",
 			valSet.Size(), len(v.Commits)))
@@ -216,7 +216,7 @@ func (valSet *ValidatorSet) VerifyValidation(hash []byte, parts types.PartSetHea
 			continue
 		}
 		_, val := valSet.GetByIndex(uint(idx))
-		commitSignBytes := account.SignBytes(&types.Vote{
+		commitSignBytes := account.SignBytes(chainID, &types.Vote{
 			Height: height, Round: commit.Round, Type: types.VoteTypeCommit,
 			BlockHash:  hash,
 			BlockParts: parts,
diff --git a/types/block.go b/types/block.go
index 25de6dd1..eef5fe89 100644
--- a/types/block.go
+++ b/types/block.go
@@ -21,9 +21,9 @@ type Block struct {
 }
 
 // Basic validation that doesn't involve state data.
-func (b *Block) ValidateBasic(lastBlockHeight uint, lastBlockHash []byte,
+func (b *Block) ValidateBasic(chainID string, lastBlockHeight uint, lastBlockHash []byte,
 	lastBlockParts PartSetHeader, lastBlockTime time.Time) error {
-	if b.ChainID != config.GetString("chain_id") {
+	if b.ChainID != chainID {
 		return errors.New("Wrong Block.Header.ChainID")
 	}
 	if b.Height != lastBlockHeight+1 {
@@ -276,7 +276,7 @@ func (data *Data) Hash() []byte {
 	if data.hash == nil {
 		bs := make([]interface{}, len(data.Txs))
 		for i, tx := range data.Txs {
-			bs[i] = account.SignBytes(tx)
+			bs[i] = account.SignBytes(config.GetString("chain_id"), tx)
 		}
 		data.hash = merkle.HashFromBinaries(bs)
 	}
diff --git a/types/tx.go b/types/tx.go
index 00fe34d7..2d365881 100644
--- a/types/tx.go
+++ b/types/tx.go
@@ -42,7 +42,7 @@ Validation Txs:
  - DupeoutTx      Validator dupes out (equivocates)
 */
 type Tx interface {
-	WriteSignBytes(w io.Writer, n *int64, err *error)
+	WriteSignBytes(chainID string, w io.Writer, n *int64, err *error)
 }
 
 // Types of Tx implementations
@@ -129,9 +129,9 @@ type SendTx struct {
 	Outputs []*TxOutput `json:"outputs"`
 }
 
-func (tx *SendTx) WriteSignBytes(w io.Writer, n *int64, err *error) {
+func (tx *SendTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
 	// We hex encode the chain_id so we don't deal with escaping issues.
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, config.GetString("chain_id"))), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, chainID)), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"inputs":[`, TxTypeSend)), w, n, err)
 	for i, in := range tx.Inputs {
 		in.WriteSignBytes(w, n, err)
@@ -163,9 +163,9 @@ type CallTx struct {
 	Data     []byte   `json:"data"`
 }
 
-func (tx *CallTx) WriteSignBytes(w io.Writer, n *int64, err *error) {
+func (tx *CallTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
 	// We hex encode the chain_id so we don't deal with escaping issues.
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, config.GetString("chain_id"))), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, chainID)), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"address":"%X","data":"%X"`, TxTypeCall, tx.Address, tx.Data)), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"fee":%v,"gas_limit":%v,"input":`, tx.Fee, tx.GasLimit)), w, n, err)
 	tx.Input.WriteSignBytes(w, n, err)
@@ -185,9 +185,9 @@ type BondTx struct {
 	UnbondTo  []*TxOutput              `json:"unbond_to"`
 }
 
-func (tx *BondTx) WriteSignBytes(w io.Writer, n *int64, err *error) {
+func (tx *BondTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
 	// We hex encode the chain_id so we don't deal with escaping issues.
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, config.GetString("chain_id"))), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, chainID)), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"inputs":[`, TxTypeBond)), w, n, err)
 	for i, in := range tx.Inputs {
 		in.WriteSignBytes(w, n, err)
@@ -219,9 +219,9 @@ type UnbondTx struct {
 	Signature account.SignatureEd25519 `json:"signature"`
 }
 
-func (tx *UnbondTx) WriteSignBytes(w io.Writer, n *int64, err *error) {
+func (tx *UnbondTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
 	// We hex encode the chain_id so we don't deal with escaping issues.
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, config.GetString("chain_id"))), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, chainID)), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"address":"%X","height":%v}]}`, TxTypeUnbond, tx.Address, tx.Height)), w, n, err)
 }
 
@@ -237,9 +237,9 @@ type RebondTx struct {
 	Signature account.SignatureEd25519 `json:"signature"`
 }
 
-func (tx *RebondTx) WriteSignBytes(w io.Writer, n *int64, err *error) {
+func (tx *RebondTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
 	// We hex encode the chain_id so we don't deal with escaping issues.
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, config.GetString("chain_id"))), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, chainID)), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"address":"%X","height":%v}]}`, TxTypeRebond, tx.Address, tx.Height)), w, n, err)
 }
 
@@ -255,7 +255,7 @@ type DupeoutTx struct {
 	VoteB   Vote   `json:"vote_b"`
 }
 
-func (tx *DupeoutTx) WriteSignBytes(w io.Writer, n *int64, err *error) {
+func (tx *DupeoutTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
 	panic("DupeoutTx has no sign bytes")
 }
 
@@ -265,7 +265,7 @@ func (tx *DupeoutTx) String() string {
 
 //-----------------------------------------------------------------------------
 
-func TxId(tx Tx) []byte {
-	signBytes := account.SignBytes(tx)
+func TxId(chainID string, tx Tx) []byte {
+	signBytes := account.SignBytes(chainID, tx)
 	return binary.BinaryRipemd160(signBytes)
 }
diff --git a/types/tx_test.go b/types/tx_test.go
index 88d8204f..5ac1f908 100644
--- a/types/tx_test.go
+++ b/types/tx_test.go
@@ -8,6 +8,12 @@ import (
 	_ "github.com/tendermint/tendermint/config/tendermint_test"
 )
 
+var chainID string
+
+func init() {
+	chainID = config.GetString("chain_id")
+}
+
 func TestSendTxSignable(t *testing.T) {
 	sendTx := &SendTx{
 		Inputs: []*TxInput{
@@ -33,7 +39,7 @@ func TestSendTxSignable(t *testing.T) {
 			},
 		},
 	}
-	signBytes := account.SignBytes(sendTx)
+	signBytes := account.SignBytes(chainID, sendTx)
 	signStr := string(signBytes)
 	expected := Fmt(`{"chain_id":"%X","tx":[1,{"inputs":[{"address":"696E70757431","amount":12345,"sequence":67890},{"address":"696E70757432","amount":111,"sequence":222}],"outputs":[{"address":"6F757470757431","amount":333},{"address":"6F757470757432","amount":444}]}]}`,
 		config.GetString("chain_id"))
@@ -54,7 +60,7 @@ func TestCallTxSignable(t *testing.T) {
 		Fee:      222,
 		Data:     []byte("data1"),
 	}
-	signBytes := account.SignBytes(callTx)
+	signBytes := account.SignBytes(chainID, callTx)
 	signStr := string(signBytes)
 	expected := Fmt(`{"chain_id":"%X","tx":[2,{"address":"636F6E747261637431","data":"6461746131","fee":222,"gas_limit":111,"input":{"address":"696E70757431","amount":12345,"sequence":67890}}]}`,
 		config.GetString("chain_id"))
@@ -90,7 +96,7 @@ func TestBondTxSignable(t *testing.T) {
 			},
 		},
 	}
-	signBytes := account.SignBytes(bondTx)
+	signBytes := account.SignBytes(chainID, bondTx)
 	signStr := string(signBytes)
 	expected := Fmt(`{"chain_id":"%X","tx":[17,{"inputs":[{"address":"696E70757431","amount":12345,"sequence":67890},{"address":"696E70757432","amount":111,"sequence":222}],"pub_key":[1,"3B6A27BCCEB6A42D62A3A8D02A6F0D73653215771DE243A63AC048A18B59DA29"],"unbond_to":[{"address":"6F757470757431","amount":333},{"address":"6F757470757432","amount":444}]}]}`,
 		config.GetString("chain_id"))
@@ -104,7 +110,7 @@ func TestUnbondTxSignable(t *testing.T) {
 		Address: []byte("address1"),
 		Height:  111,
 	}
-	signBytes := account.SignBytes(unbondTx)
+	signBytes := account.SignBytes(chainID, unbondTx)
 	signStr := string(signBytes)
 	expected := Fmt(`{"chain_id":"%X","tx":[18,{"address":"6164647265737331","height":111}]}`,
 		config.GetString("chain_id"))
@@ -118,7 +124,7 @@ func TestRebondTxSignable(t *testing.T) {
 		Address: []byte("address1"),
 		Height:  111,
 	}
-	signBytes := account.SignBytes(rebondTx)
+	signBytes := account.SignBytes(chainID, rebondTx)
 	signStr := string(signBytes)
 	expected := Fmt(`{"chain_id":"%X","tx":[19,{"address":"6164647265737331","height":111}]}`,
 		config.GetString("chain_id"))
diff --git a/types/tx_utils.go b/types/tx_utils.go
index 29a7b3ab..eb5491ad 100644
--- a/types/tx_utils.go
+++ b/types/tx_utils.go
@@ -56,12 +56,12 @@ func (tx *SendTx) AddOutput(addr []byte, amt uint64) error {
 	return nil
 }
 
-func (tx *SendTx) SignInput(i int, privAccount *account.PrivAccount) error {
+func (tx *SendTx) SignInput(chainID string, i int, privAccount *account.PrivAccount) error {
 	if i >= len(tx.Inputs) {
 		return fmt.Errorf("Index %v is greater than number of inputs (%v)", i, len(tx.Inputs))
 	}
 	tx.Inputs[i].PubKey = privAccount.PubKey
-	tx.Inputs[i].Signature = privAccount.Sign(tx)
+	tx.Inputs[i].Signature = privAccount.Sign(chainID, tx)
 	return nil
 }
 
@@ -98,9 +98,9 @@ func NewCallTxWithNonce(from account.PubKey, to, data []byte, amt, gasLimit, fee
 	}
 }
 
-func (tx *CallTx) Sign(privAccount *account.PrivAccount) {
+func (tx *CallTx) Sign(chainID string, privAccount *account.PrivAccount) {
 	tx.Input.PubKey = privAccount.PubKey
-	tx.Input.Signature = privAccount.Sign(tx)
+	tx.Input.Signature = privAccount.Sign(chainID, tx)
 }
 
 //----------------------------------------------------------------------------
@@ -155,8 +155,8 @@ func (tx *BondTx) AddOutput(addr []byte, amt uint64) error {
 	return nil
 }
 
-func (tx *BondTx) SignBond(privAccount *account.PrivAccount) error {
-	sig := privAccount.Sign(tx)
+func (tx *BondTx) SignBond(chainID string, privAccount *account.PrivAccount) error {
+	sig := privAccount.Sign(chainID, tx)
 	sigEd, ok := sig.(account.SignatureEd25519)
 	if !ok {
 		return fmt.Errorf("Bond signer must be ED25519")
@@ -165,11 +165,11 @@ func (tx *BondTx) SignBond(privAccount *account.PrivAccount) error {
 	return nil
 }
 
-func (tx *BondTx) SignInput(i int, privAccount *account.PrivAccount) error {
+func (tx *BondTx) SignInput(chainID string, i int, privAccount *account.PrivAccount) error {
 	if i >= len(tx.Inputs) {
 		return fmt.Errorf("Index %v is greater than number of inputs (%v)", i, len(tx.Inputs))
 	}
 	tx.Inputs[i].PubKey = privAccount.PubKey
-	tx.Inputs[i].Signature = privAccount.Sign(tx)
+	tx.Inputs[i].Signature = privAccount.Sign(chainID, tx)
 	return nil
 }
diff --git a/types/vote.go b/types/vote.go
index d733f72d..def488e9 100644
--- a/types/vote.go
+++ b/types/vote.go
@@ -45,9 +45,9 @@ const (
 	VoteTypeCommit    = byte(0x03)
 )
 
-func (vote *Vote) WriteSignBytes(w io.Writer, n *int64, err *error) {
+func (vote *Vote) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
 	// We hex encode the chain_id name so we don't deal with escaping issues.
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, config.GetString("chain_id"))), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":"%X"`, chainID)), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"vote":{"block_hash":"%X","block_parts":%v`, vote.BlockHash, vote.BlockParts)), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"height":%v,"round":%v,"type":%v}}`, vote.Height, vote.Round, vote.Type)), w, n, err)
 }