diff --git a/state/execution.go b/state/execution.go
index 529d4b63a..f8f4227af 100644
--- a/state/execution.go
+++ b/state/execution.go
@@ -13,7 +13,7 @@ import (
 func ExecTx(s *State, pgz *types.Plugins, tx types.Tx, isCheckTx bool, evc events.Fireable) tmsp.Result {
 
 	// TODO: do something with fees
-	fees := int64(0)
+	fees := types.Coins{}
 	chainID := s.GetChainID()
 
 	// Get the state. If isCheckTx, then we use a cache.
@@ -50,11 +50,10 @@ func ExecTx(s *State, pgz *types.Plugins, tx types.Tx, isCheckTx bool, evc event
 		if res.IsErr() {
 			return res.PrependLog("in validateOutputs()")
 		}
-		if outTotal > inTotal {
-			return tmsp.ErrBaseInsufficientFunds
+		if !inTotal.IsEqual(outTotal.Plus(types.Coins{{"", tx.Fee}})) {
+			return tmsp.ErrBaseInvalidOutput.AppendLog("Input total != output total + fees")
 		}
-		fee := inTotal - outTotal
-		fees += fee
+		fees = fees.Plus(types.Coins{{"", tx.Fee}})
 
 		// TODO: Fee validation for SendTx
 
@@ -97,7 +96,7 @@ func ExecTx(s *State, pgz *types.Plugins, tx types.Tx, isCheckTx bool, evc event
 			log.Info(Fmt("validateInput failed on %X: %v", tx.Input.Address, res))
 			return res.PrependLog("in validateInput()")
 		}
-		if tx.Input.Amount < tx.Fee {
+		if !tx.Input.Coins.IsGTE(types.Coins{{"", tx.Fee}}) {
 			log.Info(Fmt("Sender did not send enough to cover the fee %X", tx.Input.Address))
 			return tmsp.ErrBaseInsufficientFunds
 		}
@@ -110,9 +109,9 @@ func ExecTx(s *State, pgz *types.Plugins, tx types.Tx, isCheckTx bool, evc event
 		}
 
 		// Good!
-		value := tx.Input.Amount - tx.Fee
+		coins := tx.Input.Coins.Minus(types.Coins{{"", tx.Fee}})
 		inAcc.Sequence += 1
-		inAcc.Balance -= tx.Input.Amount
+		inAcc.Balance = inAcc.Balance.Minus(tx.Input.Coins)
 
 		// If this is a CheckTx, stop now.
 		if isCheckTx {
@@ -126,8 +125,7 @@ func ExecTx(s *State, pgz *types.Plugins, tx types.Tx, isCheckTx bool, evc event
 		// Run the tx.
 		cache := types.NewAccountCache(state)
 		cache.SetAccount(tx.Input.Address, inAcc)
-		gas := int64(1) // TODO
-		ctx := types.NewCallContext(cache, inAcc, value, &gas)
+		ctx := types.NewCallContext(cache, inAcc, coins)
 		res = plugin.RunTx(ctx, tx.Data)
 		if res.IsOK() {
 			cache.Sync()
@@ -145,9 +143,10 @@ func ExecTx(s *State, pgz *types.Plugins, tx types.Tx, isCheckTx bool, evc event
 			*/
 		} else {
 			log.Info("AppTx failed", "error", res)
-			// Just return the value and return.
-			// TODO: return gas?
-			inAccCopy.Balance += value
+			// Just return the coins and return.
+			inAccCopy.Balance = inAccCopy.Balance.Plus(coins)
+			// But take the gas
+			// TODO
 			state.SetAccount(tx.Input.Address, inAccCopy)
 		}
 		return res
@@ -199,7 +198,6 @@ func getOrMakeOutputs(state types.AccountGetter, accounts map[string]*types.Acco
 			acc = &types.Account{
 				PubKey:   nil,
 				Sequence: 0,
-				Balance:  0,
 			}
 		}
 		accounts[string(out.Address)] = acc
@@ -229,8 +227,8 @@ func checkInputPubKey(address []byte, acc *types.Account, in types.TxInput) tmsp
 	return tmsp.OK
 }
 
-// Validate inputs and compute total amount
-func validateInputs(accounts map[string]*types.Account, signBytes []byte, ins []types.TxInput) (total int64, res tmsp.Result) {
+// Validate inputs and compute total amount of coins
+func validateInputs(accounts map[string]*types.Account, signBytes []byte, ins []types.TxInput) (total types.Coins, res tmsp.Result) {
 
 	for _, in := range ins {
 		acc := accounts[string(in.Address)]
@@ -242,7 +240,7 @@ func validateInputs(accounts map[string]*types.Account, signBytes []byte, ins []
 			return
 		}
 		// Good. Add amount to total
-		total += in.Amount
+		total = total.Plus(in.Coins)
 	}
 	return total, tmsp.OK
 }
@@ -252,13 +250,13 @@ func validateInput(acc *types.Account, signBytes []byte, in types.TxInput) (res
 	if res := in.ValidateBasic(); res.IsErr() {
 		return res
 	}
-	// Check sequence/balance
+	// Check sequence/coins
 	seq, balance := acc.Sequence, acc.Balance
 	if seq+1 != in.Sequence {
 		return tmsp.ErrBaseInvalidSequence.AppendLog(Fmt("Got %v, expected %v. (acc.seq=%v)", in.Sequence, seq+1, acc.Sequence))
 	}
 	// Check amount
-	if balance < in.Amount {
+	if !balance.IsGTE(in.Coins) {
 		return tmsp.ErrBaseInsufficientFunds
 	}
 	// Check signatures
@@ -268,14 +266,14 @@ func validateInput(acc *types.Account, signBytes []byte, in types.TxInput) (res
 	return tmsp.OK
 }
 
-func validateOutputs(outs []types.TxOutput) (total int64, res tmsp.Result) {
+func validateOutputs(outs []types.TxOutput) (total types.Coins, res tmsp.Result) {
 	for _, out := range outs {
 		// Check TxOutput basic
 		if res := out.ValidateBasic(); res.IsErr() {
-			return 0, res
+			return nil, res
 		}
 		// Good. Add amount to total
-		total += out.Amount
+		total = total.Plus(out.Coins)
 	}
 	return total, tmsp.OK
 }
@@ -286,10 +284,10 @@ func adjustByInputs(state types.AccountSetter, accounts map[string]*types.Accoun
 		if acc == nil {
 			PanicSanity("adjustByInputs() expects account in accounts")
 		}
-		if acc.Balance < in.Amount {
+		if !acc.Balance.IsGTE(in.Coins) {
 			PanicSanity("adjustByInputs() expects sufficient funds")
 		}
-		acc.Balance -= in.Amount
+		acc.Balance = acc.Balance.Minus(in.Coins)
 		acc.Sequence += 1
 		state.SetAccount(in.Address, acc)
 	}
@@ -301,7 +299,7 @@ func adjustByOutputs(state types.AccountSetter, accounts map[string]*types.Accou
 		if acc == nil {
 			PanicSanity("adjustByOutputs() expects account in accounts")
 		}
-		acc.Balance += out.Amount
+		acc.Balance = acc.Balance.Plus(out.Coins)
 		if !isCheckTx {
 			state.SetAccount(out.Address, acc)
 		}
diff --git a/tests/common.go b/tests/common.go
index 3f9e8e5e8..1a9f3aee3 100644
--- a/tests/common.go
+++ b/tests/common.go
@@ -15,7 +15,6 @@ func PrivAccountFromSecret(secret string) types.PrivAccount {
 		Account: types.Account{
 			PubKey:   privKey.PubKey(),
 			Sequence: 0,
-			Balance:  0,
 		},
 	}
 	return privAccount
@@ -38,7 +37,7 @@ func RandAccounts(num int, minAmount int64, maxAmount int64) []types.PrivAccount
 			Account: types.Account{
 				PubKey:   pubKey,
 				Sequence: 0,
-				Balance:  balance,
+				Balance:  types.Coins{types.Coin{"", balance}},
 			},
 		}
 	}
diff --git a/tests/tendermint/main.go b/tests/tendermint/main.go
index 0dbfedfa6..a221d4b00 100644
--- a/tests/tendermint/main.go
+++ b/tests/tendermint/main.go
@@ -51,14 +51,14 @@ func main() {
 				types.TxInput{
 					Address:  root.Account.PubKey.Address(),
 					PubKey:   root.Account.PubKey, // TODO is this needed?
-					Amount:   1000002,
+					Coins:    types.Coins{{"", 1000002}},
 					Sequence: sequence,
 				},
 			},
 			Outputs: []types.TxOutput{
 				types.TxOutput{
 					Address: privAccount.Account.PubKey.Address(),
-					Amount:  1000000,
+					Coins:   types.Coins{{"", 1000000}},
 				},
 			},
 		}
@@ -102,14 +102,14 @@ func main() {
 				types.TxInput{
 					Address:  privAccountA.Account.PubKey.Address(),
 					PubKey:   privAccountA.Account.PubKey,
-					Amount:   3,
+					Coins:    types.Coins{{"", 3}},
 					Sequence: privAccountASequence + 1,
 				},
 			},
 			Outputs: []types.TxOutput{
 				types.TxOutput{
 					Address: privAccountB.Account.PubKey.Address(),
-					Amount:  1,
+					Coins:   types.Coins{{"", 1}},
 				},
 			},
 		}
diff --git a/tests/tmsp/main.go b/tests/tmsp/main.go
index c5d1e7254..e2072367d 100644
--- a/tests/tmsp/main.go
+++ b/tests/tmsp/main.go
@@ -28,24 +28,26 @@ func testSendTx() {
 
 	// Seed Basecoin with account
 	tAcc := tPriv.Account
-	tAcc.Balance = 1000
+	tAcc.Balance = types.Coins{{"", 1000}}
 	fmt.Println(bcApp.SetOption("base/chainID", "test_chain_id"))
 	fmt.Println(bcApp.SetOption("base/account", string(wire.JSONBytes(tAcc))))
 
 	// Construct a SendTx signature
 	tx := &types.SendTx{
+		Fee: 0,
+		Gas: 0,
 		Inputs: []types.TxInput{
 			types.TxInput{
 				Address:  tPriv.Account.PubKey.Address(),
 				PubKey:   tPriv.Account.PubKey, // TODO is this needed?
-				Amount:   1,
+				Coins:    types.Coins{{"", 1}},
 				Sequence: 1,
 			},
 		},
 		Outputs: []types.TxOutput{
 			types.TxOutput{
 				Address: tPriv2.Account.PubKey.Address(),
-				Amount:  1,
+				Coins:   types.Coins{{"", 1}},
 			},
 		},
 	}
@@ -95,7 +97,7 @@ func testSequence() {
 	// Get the root account
 	root := tests.PrivAccountFromSecret("test")
 	rootAcc := root.Account
-	rootAcc.Balance = 1 << 53
+	rootAcc.Balance = types.Coins{{"", 1 << 53}}
 	fmt.Println(bcApp.SetOption("base/chainID", "test_chain_id"))
 	fmt.Println(bcApp.SetOption("base/account", string(wire.JSONBytes(rootAcc))))
 
@@ -108,18 +110,20 @@ func testSequence() {
 	for i := 0; i < len(privAccounts); i++ {
 		privAccount := privAccounts[i]
 		tx := &types.SendTx{
+			Fee: 2,
+			Gas: 2,
 			Inputs: []types.TxInput{
 				types.TxInput{
 					Address:  root.Account.PubKey.Address(),
 					PubKey:   root.Account.PubKey, // TODO is this needed?
-					Amount:   1000002,
+					Coins:    types.Coins{{"", 1000002}},
 					Sequence: sequence,
 				},
 			},
 			Outputs: []types.TxOutput{
 				types.TxOutput{
 					Address: privAccount.Account.PubKey.Address(),
-					Amount:  1000000,
+					Coins:   types.Coins{{"", 1000000}},
 				},
 			},
 		}
@@ -155,18 +159,20 @@ func testSequence() {
 		privAccountB := privAccounts[randB]
 
 		tx := &types.SendTx{
+			Fee: 2,
+			Gas: 2,
 			Inputs: []types.TxInput{
 				types.TxInput{
 					Address:  privAccountA.Account.PubKey.Address(),
 					PubKey:   privAccountA.Account.PubKey,
-					Amount:   3,
+					Coins:    types.Coins{{"", 3}},
 					Sequence: privAccountASequence + 1,
 				},
 			},
 			Outputs: []types.TxOutput{
 				types.TxOutput{
 					Address: privAccountB.Account.PubKey.Address(),
-					Amount:  1,
+					Coins:   types.Coins{{"", 1}},
 				},
 			},
 		}
diff --git a/types/account.go b/types/account.go
index 3591407a5..d78f560a6 100644
--- a/types/account.go
+++ b/types/account.go
@@ -9,7 +9,7 @@ import (
 type Account struct {
 	PubKey   crypto.PubKey `json:"pub_key"` // May be nil, if not known.
 	Sequence int           `json:"sequence"`
-	Balance  int64         `json:"balance"`
+	Balance  Coins         `json:"coins"`
 }
 
 func (acc *Account) Copy() *Account {
diff --git a/types/coin.go b/types/coin.go
new file mode 100644
index 000000000..bc2bd806e
--- /dev/null
+++ b/types/coin.go
@@ -0,0 +1,130 @@
+package types
+
+import (
+	"fmt"
+	"strings"
+)
+
+type Coin struct {
+	Denom  string `json:"denom"`
+	Amount int64  `json:"amount"`
+}
+
+func (coin Coin) String() string {
+	return fmt.Sprintf("(%v %v)",
+		coin.Denom, coin.Amount)
+}
+
+//----------------------------------------
+
+type Coins []Coin
+
+// Must be sorted, and not have 0 amounts
+func (coins Coins) IsValid() bool {
+	switch len(coins) {
+	case 0:
+		return true
+	case 1:
+		return coins[0].Amount != 0
+	default:
+		lowDenom := coins[0].Denom
+		for _, coin := range coins[1:] {
+			if coin.Denom <= lowDenom {
+				return false
+			}
+			if coin.Amount == 0 {
+				return false
+			}
+		}
+		return true
+	}
+}
+
+func (coinsA Coins) Plus(coinsB Coins) Coins {
+	sum := []Coin{}
+	indexA, indexB := 0, 0
+	lenA, lenB := len(coinsA), len(coinsB)
+	for {
+		if indexA == lenA {
+			if indexB == lenB {
+				return sum
+			} else {
+				return append(sum, coinsB[indexB:]...)
+			}
+		} else if indexB == lenB {
+			return append(sum, coinsA[indexA:]...)
+		}
+		coinA, coinB := coinsA[indexA], coinsB[indexB]
+		switch strings.Compare(coinA.Denom, coinB.Denom) {
+		case -1:
+			sum = append(sum, coinA)
+			indexA += 1
+		case 0:
+			if coinA.Amount+coinB.Amount == 0 {
+				// ignore 0 sum coin type
+			} else {
+				sum = append(sum, Coin{
+					Denom:  coinA.Denom,
+					Amount: coinA.Amount + coinB.Amount,
+				})
+			}
+			indexA += 1
+			indexB += 1
+		case 1:
+			sum = append(sum, coinB)
+			indexB += 1
+		}
+	}
+	return sum
+}
+
+func (coins Coins) Negative() Coins {
+	res := make([]Coin, 0, len(coins))
+	for _, coin := range coins {
+		res = append(res, Coin{
+			Denom:  coin.Denom,
+			Amount: -coin.Amount,
+		})
+	}
+	return res
+}
+
+func (coinsA Coins) Minus(coinsB Coins) Coins {
+	return coinsA.Plus(coinsB.Negative())
+}
+
+func (coinsA Coins) IsGTE(coinsB Coins) bool {
+	diff := coinsA.Minus(coinsB)
+	if len(diff) == 0 {
+		return true
+	}
+	return diff.IsPositive()
+}
+
+func (coins Coins) IsZero() bool {
+	return len(coins) == 0
+}
+
+func (coinsA Coins) IsEqual(coinsB Coins) bool {
+	if len(coinsA) != len(coinsB) {
+		return false
+	}
+	for i := 0; i < len(coinsA); i++ {
+		if coinsA[i] != coinsB[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func (coins Coins) IsPositive() bool {
+	if len(coins) == 0 {
+		return false
+	}
+	for _, coinAmount := range coins {
+		if coinAmount.Amount <= 0 {
+			return false
+		}
+	}
+	return true
+}
diff --git a/types/coin_test.go b/types/coin_test.go
new file mode 100644
index 000000000..00a07a6f3
--- /dev/null
+++ b/types/coin_test.go
@@ -0,0 +1,67 @@
+package types
+
+import (
+	"testing"
+)
+
+func TestCoins(t *testing.T) {
+	coins := Coins{
+		Coin{"GAS", 1},
+		Coin{"MINERAL", 1},
+		Coin{"TREE", 1},
+	}
+
+	if !coins.IsValid() {
+		t.Fatal("Coins are valid")
+	}
+
+	if !coins.IsPositive() {
+		t.Fatalf("Expected coins to be positive: %v", coins)
+	}
+
+	negCoins := coins.Negative()
+	if negCoins.IsPositive() {
+		t.Fatalf("Expected neg coins to not be positive: %v", negCoins)
+	}
+
+	sumCoins := coins.Plus(negCoins)
+	if len(sumCoins) != 0 {
+		t.Fatal("Expected 0 coins")
+	}
+}
+
+func TestCoinsBadSort(t *testing.T) {
+	coins := Coins{
+		Coin{"TREE", 1},
+		Coin{"GAS", 1},
+		Coin{"MINERAL", 1},
+	}
+
+	if coins.IsValid() {
+		t.Fatal("Coins are not sorted")
+	}
+}
+
+func TestCoinsBadAmount(t *testing.T) {
+	coins := Coins{
+		Coin{"GAS", 1},
+		Coin{"TREE", 0},
+		Coin{"MINERAL", 1},
+	}
+
+	if coins.IsValid() {
+		t.Fatal("Coins cannot include 0 amounts")
+	}
+}
+
+func TestCoinsDuplicate(t *testing.T) {
+	coins := Coins{
+		Coin{"GAS", 1},
+		Coin{"GAS", 1},
+		Coin{"MINERAL", 1},
+	}
+
+	if coins.IsValid() {
+		t.Fatal("Duplicate coin")
+	}
+}
diff --git a/types/plugin.go b/types/plugin.go
index 3ab6f176b..35f2239f7 100644
--- a/types/plugin.go
+++ b/types/plugin.go
@@ -5,8 +5,6 @@ import (
 )
 
 // Value is any floating value.  It must be given to someone.
-// Gas is a pointer to remainig gas.  Decrement as you go,
-// if any gas is left the user is
 type Plugin interface {
 	SetOption(key string, value string) (log string)
 	RunTx(ctx CallContext, txBytes []byte) (res tmsp.Result)
@@ -25,16 +23,14 @@ type NamedPlugin struct {
 type CallContext struct {
 	Cache  AccountCacher
 	Caller *Account
-	Value  int64
-	Gas    *int64
+	Coins  Coins
 }
 
-func NewCallContext(cache AccountCacher, caller *Account, value int64, gas *int64) CallContext {
+func NewCallContext(cache AccountCacher, caller *Account, coins Coins) CallContext {
 	return CallContext{
 		Cache:  cache,
 		Caller: caller,
-		Value:  value,
-		Gas:    gas,
+		Coins:  coins,
 	}
 }
 
diff --git a/types/tx.go b/types/tx.go
index 774f7d465..8e6577432 100644
--- a/types/tx.go
+++ b/types/tx.go
@@ -42,7 +42,7 @@ var _ = wire.RegisterInterface(
 
 type TxInput struct {
 	Address   []byte           `json:"address"`   // Hash of the PubKey
-	Amount    int64            `json:"amount"`    // Must not exceed account balance
+	Coins     Coins            `json:"coins"`     //
 	Sequence  int              `json:"sequence"`  // Must be 1 greater than the last committed TxInput
 	Signature crypto.Signature `json:"signature"` // Depends on the PubKey type and the whole Tx
 	PubKey    crypto.PubKey    `json:"pub_key"`   // May be nil
@@ -50,42 +50,50 @@ type TxInput struct {
 
 func (txIn TxInput) ValidateBasic() tmsp.Result {
 	if len(txIn.Address) != 20 {
-		return tmsp.ErrBaseInvalidAddress.AppendLog("(in TxInput)")
+		return tmsp.ErrBaseInvalidInput.AppendLog("Invalid address length")
 	}
-	if txIn.Amount == 0 {
-		return tmsp.ErrBaseInvalidAmount.AppendLog("(in TxInput)")
+	if !txIn.Coins.IsValid() {
+		return tmsp.ErrBaseInvalidInput.AppendLog(Fmt("Invalid coins %v", txIn.Coins))
+	}
+	if txIn.Coins.IsZero() {
+		return tmsp.ErrBaseInvalidInput.AppendLog("Coins cannot be zero")
 	}
 	return tmsp.OK
 }
 
 func (txIn TxInput) String() string {
-	return Fmt("TxInput{%X,%v,%v,%v,%v}", txIn.Address, txIn.Amount, txIn.Sequence, txIn.Signature, txIn.PubKey)
+	return Fmt("TxInput{%X,%v,%v,%v,%v}", txIn.Address, txIn.Coins, txIn.Sequence, txIn.Signature, txIn.PubKey)
 }
 
 //-----------------------------------------------------------------------------
 
 type TxOutput struct {
 	Address []byte `json:"address"` // Hash of the PubKey
-	Amount  int64  `json:"amount"`  // The sum of all outputs must not exceed the inputs.
+	Coins   Coins  `json:"coins"`   //
 }
 
 func (txOut TxOutput) ValidateBasic() tmsp.Result {
 	if len(txOut.Address) != 20 {
-		return tmsp.ErrBaseInvalidAddress.AppendLog("(in TxOutput)")
+		return tmsp.ErrBaseInvalidOutput.AppendLog("Invalid address length")
 	}
-	if txOut.Amount == 0 {
-		return tmsp.ErrBaseInvalidAmount.AppendLog("(in TxOutput)")
+	if !txOut.Coins.IsValid() {
+		return tmsp.ErrBaseInvalidOutput.AppendLog(Fmt("Invalid coins %v", txOut.Coins))
+	}
+	if txOut.Coins.IsZero() {
+		return tmsp.ErrBaseInvalidOutput.AppendLog("Coins cannot be zero")
 	}
 	return tmsp.OK
 }
 
 func (txOut TxOutput) String() string {
-	return Fmt("TxOutput{%X,%v}", txOut.Address, txOut.Amount)
+	return Fmt("TxOutput{%X,%v}", txOut.Address, txOut.Coins)
 }
 
 //-----------------------------------------------------------------------------
 
 type SendTx struct {
+	Fee     int64      `json:"fee"` // Fee
+	Gas     int64      `json:"gas"` // Gas
 	Inputs  []TxInput  `json:"inputs"`
 	Outputs []TxOutput `json:"outputs"`
 }
@@ -105,16 +113,16 @@ func (tx *SendTx) SignBytes(chainID string) []byte {
 }
 
 func (tx *SendTx) String() string {
-	return Fmt("SendTx{%v -> %v}", tx.Inputs, tx.Outputs)
+	return Fmt("SendTx{%v/%v %v->%v}", tx.Fee, tx.Gas, tx.Inputs, tx.Outputs)
 }
 
 //-----------------------------------------------------------------------------
 
 type AppTx struct {
-	Type  byte    `json:"type"` // Which app
-	Gas   int64   `json:"gas"`
-	Fee   int64   `json:"fee"`
-	Input TxInput `json:"input"`
+	Fee   int64   `json:"fee"`   // Fee
+	Gas   int64   `json:"gas"`   // Gas
+	Type  byte    `json:"type"`  // Which app
+	Input TxInput `json:"input"` // Hmmm do we want coins?
 	Data  []byte  `json:"data"`
 }
 
@@ -128,7 +136,7 @@ func (tx *AppTx) SignBytes(chainID string) []byte {
 }
 
 func (tx *AppTx) String() string {
-	return Fmt("AppTx{%v %v %v %v -> %X}", tx.Type, tx.Gas, tx.Fee, tx.Input, tx.Data)
+	return Fmt("AppTx{%v/%v %v %v %X}", tx.Fee, tx.Gas, tx.Type, tx.Input, tx.Data)
 }
 
 //-----------------------------------------------------------------------------
diff --git a/types/tx_test.go b/types/tx_test.go
index 49530424f..92d54883c 100644
--- a/types/tx_test.go
+++ b/types/tx_test.go
@@ -10,32 +10,34 @@ var chainID string = "test_chain"
 
 func TestSendTxSignable(t *testing.T) {
 	sendTx := &SendTx{
+		Fee: 111,
+		Gas: 222,
 		Inputs: []TxInput{
 			TxInput{
 				Address:  []byte("input1"),
-				Amount:   12345,
+				Coins:    Coins{{"", 12345}},
 				Sequence: 67890,
 			},
 			TxInput{
 				Address:  []byte("input2"),
-				Amount:   111,
+				Coins:    Coins{{"", 111}},
 				Sequence: 222,
 			},
 		},
 		Outputs: []TxOutput{
 			TxOutput{
 				Address: []byte("output1"),
-				Amount:  333,
+				Coins:   Coins{{"", 333}},
 			},
 			TxOutput{
 				Address: []byte("output2"),
-				Amount:  444,
+				Coins:   Coins{{"", 444}},
 			},
 		},
 	}
 	signBytes := sendTx.SignBytes(chainID)
 	signBytesHex := Fmt("%X", signBytes)
-	expected := "010A746573745F636861696E0101020106696E7075743100000000000030390301093200000106696E70757432000000000000006F01DE0000010201076F757470757431000000000000014D01076F75747075743200000000000001BC"
+	expected := "010A746573745F636861696E01000000000000006F00000000000000DE01020106696E7075743101010000000000000030390301093200000106696E70757432010100000000000000006F01DE0000010201076F757470757431010100000000000000014D01076F75747075743201010000000000000001BC"
 	if signBytesHex != expected {
 		t.Errorf("Got unexpected sign string for SendTx. Expected:\n%v\nGot:\n%v", expected, signBytesHex)
 	}
@@ -43,19 +45,19 @@ func TestSendTxSignable(t *testing.T) {
 
 func TestAppTxSignable(t *testing.T) {
 	callTx := &AppTx{
+		Fee:  111,
+		Gas:  222,
 		Type: 0x01,
-		Gas:  111,
-		Fee:  222,
 		Input: TxInput{
 			Address:  []byte("input1"),
-			Amount:   12345,
+			Coins:    Coins{{"", 12345}},
 			Sequence: 67890,
 		},
 		Data: []byte("data1"),
 	}
 	signBytes := callTx.SignBytes(chainID)
 	signBytesHex := Fmt("%X", signBytes)
-	expected := "010A746573745F636861696E0101000000000000006F00000000000000DE0106696E70757431000000000000303903010932000001056461746131"
+	expected := "010A746573745F636861696E01000000000000006F00000000000000DE010106696E70757431010100000000000000303903010932000001056461746131"
 	if signBytesHex != expected {
 		t.Errorf("Got unexpected sign string for AppTx. Expected:\n%v\nGot:\n%v", expected, signBytesHex)
 	}