diff --git a/types/errors.go b/types/errors.go
index 1115d39376..48ca8287a0 100644
--- a/types/errors.go
+++ b/types/errors.go
@@ -109,6 +109,10 @@ func ErrInvalidCoins(msg string) Error {
 	return newError(CodeInvalidCoins, msg)
 }
 
+func ErrInvalidCoins(coins Coins) Error {
+	return newError(CodeInvalidCoins, coins.String())
+}
+
 //----------------------------------------
 // Error & sdkError
 
diff --git a/types/rational.go b/types/rational.go
index 907ff2f319..3fe1a31742 100644
--- a/types/rational.go
+++ b/types/rational.go
@@ -1,6 +1,9 @@
 package types
 
 import (
+	"bytes"
+	"encoding/json"
+	"fmt"
 	"math/big"
 	"strconv"
 	"strings"
@@ -13,12 +16,21 @@ import (
 //  __|     |_    |_
 
 // Rat - extend big.Rat
+// NOTE: never use new(Rat) or else
+// we will panic unmarshalling into the
+// nil embedded big.Rat
 type Rat struct {
 	*big.Rat `json:"rat"`
 }
 
-// Rational - big Rat with additional functionality
-type Rational interface {
+type Rational = Rat
+
+// RationalInterface - big Rat with additional functionality
+// NOTE: we only have one implementation of this interface
+// and don't use it anywhere, but it might come in handy
+// if we want to provide Rational types that include
+// the units of the value in the type system.
+type RationalInterface interface {
 	GetRat() *big.Rat
 	Num() int64
 	Denom() int64
@@ -200,6 +212,37 @@ func (r Rat) Round(precisionFactor int64) Rational {
 //return nil
 //}
 
-//nolint
-func (r Rat) MarshalJSON() ([]byte, error)           { return r.MarshalText() }
-func (r *Rat) UnmarshalJSON(data []byte) (err error) { return r.UnmarshalText(data) }
+var ratCdc JSONCodec // TODO wire.Codec
+
+// Hack to just use json.Marshal for everything until
+// we update for amino
+type JSONCodec struct{}
+
+func (jc JSONCodec) MarshalJSON(o interface{}) ([]byte, error) {
+	return json.Marshal(o)
+}
+
+func (jc JSONCodec) UnmarshalJSON(bz []byte, o interface{}) error {
+	return json.Unmarshal(bz, o)
+}
+
+// Wraps r.MarshalText() in quotes to make it a valid JSON string.
+func (r Rat) MarshalJSON() ([]byte, error) {
+	bz, err := r.MarshalText()
+	if err != nil {
+		return bz, err
+	}
+	return []byte(fmt.Sprintf(`"%s"`, bz)), nil
+}
+
+// Requires a valid JSON string - strings quotes and calls UnmarshalText
+func (r *Rat) UnmarshalJSON(data []byte) (err error) {
+	quote := []byte(`"`)
+	if len(data) < 2 ||
+		!bytes.HasPrefix(data, quote) ||
+		!bytes.HasSuffix(data, quote) {
+		return fmt.Errorf("JSON encoded Rat must be a quote-delimitted string")
+	}
+	data = bytes.Trim(data, `"`)
+	return r.UnmarshalText(data)
+}
diff --git a/types/rational_test.go b/types/rational_test.go
index 9376a8e463..3794627789 100644
--- a/types/rational_test.go
+++ b/types/rational_test.go
@@ -1,7 +1,6 @@
 package types
 
 import (
-	"encoding/json"
 	"math/big"
 	"testing"
 
@@ -193,41 +192,44 @@ func TestRound(t *testing.T) {
 }
 
 func TestZeroSerializationJSON(t *testing.T) {
-	var r Rat
-	err := json.Unmarshal([]byte("{\"numerator\":0,\"denominator\":1}"), &r)
+	r := NewRat(0, 1)
+	err := r.UnmarshalJSON([]byte(`"0/1"`))
 	assert.Nil(t, err)
-	err = json.Unmarshal([]byte("{\"numerator\":0,\"denominator\":0}"), &r)
+	err = r.UnmarshalJSON([]byte(`"0/0"`))
 	assert.NotNil(t, err)
-	err = json.Unmarshal([]byte("{\"numerator\":1,\"denominator\":0}"), &r)
+	err = r.UnmarshalJSON([]byte(`"1/0"`))
 	assert.NotNil(t, err)
-	err = json.Unmarshal([]byte("{}"), &r)
+	err = r.UnmarshalJSON([]byte(`"{}"`))
 	assert.NotNil(t, err)
 }
 
 func TestSerializationJSON(t *testing.T) {
 	r := NewRat(1, 3)
 
-	rMarshal, err := json.Marshal(r)
+	bz, err := r.MarshalText()
 	require.Nil(t, err)
 
-	var rUnmarshal Rat
-	err = json.Unmarshal(rMarshal, &rUnmarshal)
+	r2 := NewRat(0, 1)
+	err = r2.UnmarshalText(bz)
 	require.Nil(t, err)
 
-	assert.True(t, r.Equal(rUnmarshal), "original: %v, unmarshalled: %v", r, rUnmarshal)
+	assert.True(t, r.Equal(r2), "original: %v, unmarshalled: %v", r, r2)
 }
 
 func TestSerializationGoWire(t *testing.T) {
 	r := NewRat(1, 3)
 
-	rMarshal, err := ratCdc.MarshalJSON(r)
+	bz, err := ratCdc.MarshalJSON(r)
 	require.Nil(t, err)
 
-	var rUnmarshal Rat
-	err = ratCdc.UnmarshalJSON(rMarshal, &rUnmarshal)
+	bz, err = r.MarshalJSON()
 	require.Nil(t, err)
 
-	assert.True(t, r.Equal(rUnmarshal), "original: %v, unmarshalled: %v", r, rUnmarshal)
+	r2 := NewRat(0, 1)
+	err = ratCdc.UnmarshalJSON(bz, &r2)
+	require.Nil(t, err)
+
+	assert.True(t, r.Equal(r2), "original: %v, unmarshalled: %v", r, r2)
 }
 
 type testEmbedStruct struct {
@@ -237,38 +239,18 @@ type testEmbedStruct struct {
 }
 
 func TestEmbeddedStructSerializationGoWire(t *testing.T) {
-	r := testEmbedStruct{"foo", 10, NewRat(1, 3)}
+	obj := testEmbedStruct{"foo", 10, NewRat(1, 3)}
 
-	rMarshal, err := ratCdc.MarshalJSON(r)
+	bz, err := ratCdc.MarshalJSON(obj)
 	require.Nil(t, err)
 
-	var rUnmarshal testEmbedStruct
-	err = ratCdc.UnmarshalJSON(rMarshal, &rUnmarshal)
+	var obj2 testEmbedStruct
+	obj2.Field3 = NewRat(0, 1) // ... needs to be initialized
+	err = ratCdc.UnmarshalJSON(bz, &obj2)
 	require.Nil(t, err)
 
-	assert.Equal(t, r.Field1, rUnmarshal.Field1)
-	assert.Equal(t, r.Field2, rUnmarshal.Field2)
-	assert.True(t, r.Field3.Equal(rUnmarshal.Field3), "original: %v, unmarshalled: %v", r, rUnmarshal)
+	assert.Equal(t, obj.Field1, obj2.Field1)
+	assert.Equal(t, obj.Field2, obj2.Field2)
+	assert.True(t, obj.Field3.Equal(obj2.Field3), "original: %v, unmarshalled: %v", obj, obj2)
 
 }
-
-type testEmbedInterface struct {
-	Field1 string   `json:"f1"`
-	Field2 int      `json:"f2"`
-	Field3 Rational `json:"f3"`
-}
-
-func TestEmbeddedInterfaceSerializationGoWire(t *testing.T) {
-	r := testEmbedInterface{"foo", 10, NewRat(1, 3)}
-
-	rMarshal, err := ratCdc.MarshalJSON(r)
-	require.Nil(t, err)
-
-	var rUnmarshal testEmbedInterface
-	err = ratCdc.UnmarshalJSON(rMarshal, &rUnmarshal)
-	require.Nil(t, err)
-
-	assert.Equal(t, r.Field1, rUnmarshal.Field1)
-	assert.Equal(t, r.Field2, rUnmarshal.Field2)
-	assert.True(t, r.Field3.Equal(rUnmarshal.Field3), "original: %v, unmarshalled: %v", r, rUnmarshal)
-}
diff --git a/x/stake/mapper.go b/x/stake/mapper.go
index b763a26828..caebe84999 100644
--- a/x/stake/mapper.go
+++ b/x/stake/mapper.go
@@ -301,7 +301,7 @@ func (m Mapper) removeDelegatorBond(delegator sdk.Address, candidateAddr sdk.Add
 			addrs = append(addrs[:i], addrs[i+1:]...)
 		}
 	}
-	b, err := m.cdc.MarshalJSON(pks)
+	b, err := m.cdc.MarshalJSON(addrs)
 	if err != nil {
 		panic(err)
 	}
diff --git a/x/stake/test_common.go b/x/stake/test_common.go
index 997b55102a..e04151046d 100644
--- a/x/stake/test_common.go
+++ b/x/stake/test_common.go
@@ -11,6 +11,7 @@ import (
 	crypto "github.com/tendermint/go-crypto"
 	dbm "github.com/tendermint/tmlibs/db"
 
+	"github.com/cosmos/cosmos-sdk/store"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
@@ -21,18 +22,18 @@ func subspace(prefix []byte) (start, end []byte) {
 	return prefix, end
 }
 
-func createTestInput(t *testing.T, isCheckTx bool) (store sdk.KVStore, ctx sdk.Context, key sdk.StoreKey) {
+func createTestInput(t *testing.T, isCheckTx bool) (sdk.KVStore, sdk.Context, sdk.StoreKey) {
 	db := dbm.NewMemDB()
-	key = sdk.NewKVStoreKey("stake")
+	key := sdk.NewKVStoreKey("stake")
 
 	ms := store.NewCommitMultiStore(db)
 	ms.MountStoreWithDB(key, sdk.StoreTypeIAVL, db)
 	err := ms.LoadLatestVersion()
 	require.Nil(t, err)
 
-	ctx = sdk.NewContext(ms, abci.Header{ChainID: "foochainid"}, isCheckTx, nil)
-	store = ms.GetKVStore(key)
-	return
+	ctx := sdk.NewContext(ms, abci.Header{ChainID: "foochainid"}, isCheckTx, nil)
+	store := ms.GetKVStore(key)
+	return store, ctx, key
 }
 
 func newAddrs(n int) (addrs []crypto.Address) {
@@ -50,7 +51,7 @@ func newPubKey(pk string) (res crypto.PubKey) {
 	//res, err = crypto.PubKeyFromBytes(pkBytes)
 	var pkEd crypto.PubKeyEd25519
 	copy(pkEd[:], pkBytes[:])
-	return pkEd
+	return pkEd.Wrap()
 }
 
 // dummy pubkeys used for testing
@@ -74,7 +75,7 @@ func candidatesFromActors(store sdk.KVStore, addrs []crypto.Address, amts []int6
 		c := &Candidate{
 			Status:      Unbonded,
 			PubKey:      pks[i],
-			Owner:       addrs[i],
+			Address:     addrs[i],
 			Assets:      sdk.NewRat(amts[i]),
 			Liabilities: sdk.NewRat(amts[i]),
 			VotingPower: sdk.NewRat(amts[i]),
@@ -83,12 +84,14 @@ func candidatesFromActors(store sdk.KVStore, addrs []crypto.Address, amts []int6
 	}
 }
 
+func saveCandidate(store sdk.KVStore, c *Candidate) {} // TODO
+
 func candidatesFromActorsEmpty(addrs []crypto.Address) (candidates Candidates) {
 	for i := 0; i < len(addrs); i++ {
 		c := &Candidate{
 			Status:      Unbonded,
 			PubKey:      pks[i],
-			Owner:       addrs[i],
+			Address:     addrs[i],
 			Assets:      sdk.ZeroRat,
 			Liabilities: sdk.ZeroRat,
 			VotingPower: sdk.ZeroRat,
diff --git a/x/stake/tick.go b/x/stake/tick.go
index 3f0d38bcd7..4b206f4dcc 100644
--- a/x/stake/tick.go
+++ b/x/stake/tick.go
@@ -22,6 +22,7 @@ func Tick(ctx sdk.Context, m Mapper) (change []*abci.Validator, err error) {
 
 	newVals := m.getValidators(params.MaxVals)
 	// XXX determine change from old validators, set to change
+	_ = newVals
 	return change, nil
 }
 
diff --git a/x/stake/tx.go b/x/stake/tx.go
index 6cae6746f9..5cc3de6d39 100644
--- a/x/stake/tx.go
+++ b/x/stake/tx.go
@@ -167,10 +167,10 @@ type MsgUnbond struct {
 	Shares string `json:"shares"`
 }
 
-func NewMsgUnbond(shares string, address sdk.Address) MsgDelegate {
+func NewMsgUnbond(bond sdk.Coin, address sdk.Address) MsgDelegate {
 	return MsgDelegate{
 		MsgAddr: NewMsgAddr(address),
-		Shares:  shares,
+		Bond:    bond, // Shares:  shares,
 	}
 }
 
@@ -202,10 +202,10 @@ func (msg MsgUnbond) ValidateBasic() sdk.Error {
 func validateCoin(coin sdk.Coin) sdk.Error {
 	coins := sdk.Coins{coin}
 	if !coins.IsValid() {
-		return sdk.ErrInvalidCoins()
+		return sdk.ErrInvalidCoins(coins)
 	}
 	if !coins.IsPositive() {
-		return fmt.Errorf("Amount must be > 0")
+		return sdk.ErrInvalidCoins(coins) // XXX: add "Amount must be > 0" ?
 	}
 	return nil
 }
diff --git a/x/stake/types.go b/x/stake/types.go
index dd5272e0df..698c7813d8 100644
--- a/x/stake/types.go
+++ b/x/stake/types.go
@@ -2,7 +2,6 @@ package stake
 
 import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
-	abci "github.com/tendermint/abci/types"
 	crypto "github.com/tendermint/go-crypto"
 )
 
@@ -167,7 +166,7 @@ type Description struct {
 func NewCandidate(pubKey crypto.PubKey, address sdk.Address, description Description) *Candidate {
 	return &Candidate{
 		Status:      Unbonded,
-		PubKey:      pubKet,
+		PubKey:      pubKey,
 		Address:     address,
 		Assets:      sdk.ZeroRat,
 		Liabilities: sdk.ZeroRat,
@@ -222,7 +221,7 @@ func (c *Candidate) removeShares(shares sdk.Rat, gs *GlobalState) (createdCoins
 // Should only be called when the Candidate qualifies as a validator.
 func (c *Candidate) validator() Validator {
 	return Validator{
-		PubKey:      c.PubKey,
+		Address:     c.Address, // XXX !!!
 		VotingPower: c.VotingPower,
 	}
 }
@@ -234,8 +233,9 @@ type Validator struct {
 }
 
 // ABCIValidator - Get the validator from a bond value
+/* TODO
 func (v Validator) ABCIValidator() (*abci.Validator, error) {
-	pkBytes, err := cdc.MarshalBinary(v.PubKey)
+	pkBytes, err := wire.MarshalBinary(v.PubKey)
 	if err != nil {
 		return nil, err
 	}
@@ -244,6 +244,7 @@ func (v Validator) ABCIValidator() (*abci.Validator, error) {
 		Power:  v.VotingPower.Evaluate(),
 	}, nil
 }
+*/
 
 //_________________________________________________________________________
 
@@ -263,11 +264,11 @@ type DelegatorBond struct {
 // Perform all the actions required to bond tokens to a delegator bond from their account
 func (bond *DelegatorBond) BondCoins(candidate *Candidate, tokens sdk.Coin, tr transact) sdk.Error {
 
-	_, err := tr.coinKeeper.SubtractCoins(tr.ctx, d.Address, sdk.Coins{tokens})
+	_, err := tr.coinKeeper.SubtractCoins(tr.ctx, candidate.Address, sdk.Coins{tokens})
 	if err != nil {
 		return err
 	}
-	newShares = candidate.addTokens(tokens.Amount, tr.gs)
+	newShares := candidate.addTokens(tokens.Amount, tr.gs)
 	bond.Shares = bond.Shares.Add(newShares)
 	return nil
 }
@@ -277,14 +278,14 @@ func (bond *DelegatorBond) UnbondCoins(candidate *Candidate, shares int64, tr tr
 
 	// subtract bond tokens from delegator bond
 	if bond.Shares.LT(shares) {
-		return ErrInsufficientFunds()
+		return sdk.ErrInsufficientFunds("") // TODO
 	}
 	bond.Shares = bond.Shares.Sub(shares)
 
 	returnAmount := candidate.removeShares(shares, tr.gs)
 	returnCoins := sdk.Coins{{tr.params.BondDenom, returnAmount}}
 
-	_, err := tr.coinKeeper.AddCoins(tr.ctx, d.Address, returnCoins)
+	_, err := tr.coinKeeper.AddCoins(tr.ctx, candidate.Address, returnCoins)
 	if err != nil {
 		return err
 	}