diff --git a/consensus/common_test.go b/consensus/common_test.go
index da7c1d8d8..23e56e67e 100644
--- a/consensus/common_test.go
+++ b/consensus/common_test.go
@@ -59,7 +59,7 @@ type validatorStub struct {
 	types.PrivValidator
 }
 
-var testMinPower = 10
+var testMinPower int64 = 10
 
 func NewValidatorStub(privValidator types.PrivValidator, valIndex int) *validatorStub {
 	return &validatorStub{
@@ -372,7 +372,7 @@ func randConsensusNet(nValidators int, testName string, tickerFunc func() Timeou
 
 // nPeers = nValidators + nNotValidator
 func randConsensusNetWithPeers(nValidators, nPeers int, testName string, tickerFunc func() TimeoutTicker, appFunc func() abci.Application) []*ConsensusState {
-	genDoc, privVals := randGenesisDoc(nValidators, false, int64(testMinPower))
+	genDoc, privVals := randGenesisDoc(nValidators, false, testMinPower)
 	css := make([]*ConsensusState, nPeers)
 	logger := consensusLogger()
 	for i := 0; i < nPeers; i++ {
diff --git a/consensus/mempool_test.go b/consensus/mempool_test.go
index 089d7b3f9..b35bdc536 100644
--- a/consensus/mempool_test.go
+++ b/consensus/mempool_test.go
@@ -8,9 +8,11 @@ import (
 
 	"github.com/stretchr/testify/assert"
 
+	"github.com/tendermint/abci/example/code"
 	abci "github.com/tendermint/abci/types"
-	"github.com/tendermint/tendermint/types"
 	cmn "github.com/tendermint/tmlibs/common"
+
+	"github.com/tendermint/tendermint/types"
 )
 
 func init() {
@@ -135,7 +137,7 @@ func TestRmBadTx(t *testing.T) {
 		// CheckTx should not err, but the app should return a bad abci code
 		// and the tx should get removed from the pool
 		err := cs.mempool.CheckTx(txBytes, func(r *abci.Response) {
-			if r.GetCheckTx().Code != abci.CodeType_BadNonce {
+			if r.GetCheckTx().Code != code.CodeTypeBadNonce {
 				t.Fatalf("expected checktx to return bad nonce, got %v", r)
 			}
 			checkTxRespCh <- struct{}{}
@@ -193,22 +195,22 @@ func (app *CounterApplication) DeliverTx(tx []byte) abci.ResponseDeliverTx {
 	txValue := txAsUint64(tx)
 	if txValue != uint64(app.txCount) {
 		return abci.ResponseDeliverTx{
-			Code: abci.CodeType_BadNonce,
+			Code: code.CodeTypeBadNonce,
 			Log:  fmt.Sprintf("Invalid nonce. Expected %v, got %v", app.txCount, txValue)}
 	}
 	app.txCount += 1
-	return abci.ResponseDeliverTx{Code: abci.CodeType_OK}
+	return abci.ResponseDeliverTx{Code: code.CodeTypeOK}
 }
 
 func (app *CounterApplication) CheckTx(tx []byte) abci.ResponseCheckTx {
 	txValue := txAsUint64(tx)
 	if txValue != uint64(app.mempoolTxCount) {
 		return abci.ResponseCheckTx{
-			Code: abci.CodeType_BadNonce,
+			Code: code.CodeTypeBadNonce,
 			Log:  fmt.Sprintf("Invalid nonce. Expected %v, got %v", app.mempoolTxCount, txValue)}
 	}
 	app.mempoolTxCount += 1
-	return abci.ResponseCheckTx{Code: abci.CodeType_OK}
+	return abci.ResponseCheckTx{Code: code.CodeTypeOK}
 }
 
 func txAsUint64(tx []byte) uint64 {
@@ -220,10 +222,10 @@ func txAsUint64(tx []byte) uint64 {
 func (app *CounterApplication) Commit() abci.ResponseCommit {
 	app.mempoolTxCount = app.txCount
 	if app.txCount == 0 {
-		return abci.ResponseCommit{Code: abci.CodeType_OK}
+		return abci.ResponseCommit{Code: code.CodeTypeOK}
 	} else {
 		hash := make([]byte, 8)
 		binary.BigEndian.PutUint64(hash, uint64(app.txCount))
-		return abci.ResponseCommit{Code: abci.CodeType_OK, Data: hash}
+		return abci.ResponseCommit{Code: code.CodeTypeOK, Data: hash}
 	}
 }
diff --git a/consensus/reactor_test.go b/consensus/reactor_test.go
index a5cf6a3fe..56ac17af5 100644
--- a/consensus/reactor_test.go
+++ b/consensus/reactor_test.go
@@ -209,7 +209,7 @@ func TestValidatorSetChanges(t *testing.T) {
 	t.Log("---------------------------- Testing adding one validator")
 
 	newValidatorPubKey1 := css[nVals].privValidator.GetPubKey()
-	newValidatorTx1 := dummy.MakeValSetChangeTx(newValidatorPubKey1.Bytes(), uint64(testMinPower))
+	newValidatorTx1 := dummy.MakeValSetChangeTx(newValidatorPubKey1.Bytes(), testMinPower)
 
 	// wait till everyone makes block 2
 	// ensure the commit includes all validators
@@ -251,10 +251,10 @@ func TestValidatorSetChanges(t *testing.T) {
 	t.Log("---------------------------- Testing adding two validators at once")
 
 	newValidatorPubKey2 := css[nVals+1].privValidator.GetPubKey()
-	newValidatorTx2 := dummy.MakeValSetChangeTx(newValidatorPubKey2.Bytes(), uint64(testMinPower))
+	newValidatorTx2 := dummy.MakeValSetChangeTx(newValidatorPubKey2.Bytes(), testMinPower)
 
 	newValidatorPubKey3 := css[nVals+2].privValidator.GetPubKey()
-	newValidatorTx3 := dummy.MakeValSetChangeTx(newValidatorPubKey3.Bytes(), uint64(testMinPower))
+	newValidatorTx3 := dummy.MakeValSetChangeTx(newValidatorPubKey3.Bytes(), testMinPower)
 
 	waitForAndValidateBlock(t, nPeers, activeVals, eventChans, css, newValidatorTx2, newValidatorTx3)
 	waitForAndValidateBlock(t, nPeers, activeVals, eventChans, css)
diff --git a/consensus/replay.go b/consensus/replay.go
index 4868656e4..168404af0 100644
--- a/consensus/replay.go
+++ b/consensus/replay.go
@@ -400,5 +400,5 @@ func (mock *mockProxyApp) EndBlock(req abci.RequestEndBlock) abci.ResponseEndBlo
 }
 
 func (mock *mockProxyApp) Commit() abci.ResponseCommit {
-	return abci.ResponseCommit{Code: abci.CodeType_OK, Data: mock.appHash}
+	return abci.ResponseCommit{Code: abci.CodeTypeOK, Data: mock.appHash}
 }
diff --git a/glide.lock b/glide.lock
index d69aacb06..fbf4b326c 100644
--- a/glide.lock
+++ b/glide.lock
@@ -1,8 +1,8 @@
-hash: 8c38726da2666831affa40474117d3cef5dad083176e81fb013d7e8493b83e6f
-updated: 2017-12-01T02:14:22.08770964Z
+hash: b0397f8c86e8131753fce91514314fe871ffb2562452a9f2125dbcd3cea600c8
+updated: 2017-12-02T23:34:41.775549968-05:00
 imports:
 - name: github.com/btcsuite/btcd
-  version: 8cea3866d0f7fb12d567a20744942c0d078c7d15
+  version: 2e60448ffcc6bf78332d1fe590260095f554dd78
   subpackages:
   - btcec
 - name: github.com/ebuchman/fail-test
@@ -28,7 +28,9 @@ imports:
 - name: github.com/gogo/protobuf
   version: 342cbe0a04158f6dcb03ca0079991a51a4248c02
   subpackages:
+  - gogoproto
   - proto
+  - protoc-gen-gogo/descriptor
 - name: github.com/golang/protobuf
   version: 1e59b77b52bf8e4b449a57e6f79f21226d571845
   subpackages:
@@ -67,7 +69,7 @@ imports:
 - name: github.com/pkg/errors
   version: 645ef00459ed84a119197bfb8d8205042c6df63d
 - name: github.com/rcrowley/go-metrics
-  version: 1f30fe9094a513ce4c700b9a54458bbb0c96996c
+  version: e181e095bae94582363434144c61a9653aff6e50
 - name: github.com/spf13/afero
   version: 8d919cbe7e2627e417f3e45c3c0e489a5b7e2536
   subpackages:
@@ -98,9 +100,10 @@ imports:
   - leveldb/table
   - leveldb/util
 - name: github.com/tendermint/abci
-  version: 22b491bb1952125dd2fb0730d6ca8e59e310547c
+  version: 48413b4839781c5c4bf96049a4b39f210ceb88c3
   subpackages:
   - client
+  - example/code
   - example/counter
   - example/dummy
   - server
@@ -113,7 +116,7 @@ imports:
 - name: github.com/tendermint/go-crypto
   version: dd20358a264c772b4a83e477b0cfce4c88a7001d
 - name: github.com/tendermint/go-wire
-  version: 5ab49b4c6ad674da6b81442911cf713ef0afb544
+  version: 217a3c439f6497890d232ff5ed24084b43d9bfb3
   subpackages:
   - data
   - data/base58
@@ -138,7 +141,7 @@ imports:
   - pubsub/query
   - test
 - name: golang.org/x/crypto
-  version: 9f005a07e0d31d45e6656d241bb5c0f2efd4bc94
+  version: 94eea52f7b742c7cbe0b03b22f0c4c8631ece122
   subpackages:
   - curve25519
   - nacl/box
@@ -149,7 +152,7 @@ imports:
   - ripemd160
   - salsa20/salsa
 - name: golang.org/x/net
-  version: 9dfe39835686865bff950a07b394c12a98ddc811
+  version: a8b9294777976932365dabb6640cf1468d95c70f
   subpackages:
   - context
   - http2
@@ -159,22 +162,22 @@ imports:
   - lex/httplex
   - trace
 - name: golang.org/x/sys
-  version: b98136db334ff9cb24f28a68e3be3cb6608f7630
+  version: 8b4580aae2a0dd0c231a45d3ccb8434ff533b840
   subpackages:
   - unix
 - name: golang.org/x/text
-  version: 88f656faf3f37f690df1a32515b479415e1a6769
+  version: 75cc3cad82b5f47d3fb229ddda8c5167da14f294
   subpackages:
   - secure/bidirule
   - transform
   - unicode/bidi
   - unicode/norm
 - name: google.golang.org/genproto
-  version: 891aceb7c239e72692819142dfca057bdcbfcb96
+  version: 7f0da29060c682909f650ad8ed4e515bd74fa12a
   subpackages:
   - googleapis/rpc/status
 - name: google.golang.org/grpc
-  version: f7bf885db0b7479a537ec317c6e48ce53145f3db
+  version: 401e0e00e4bb830a10496d64cd95e068c5bf50de
   subpackages:
   - balancer
   - codes
diff --git a/glide.yaml b/glide.yaml
index 18f0dae8d..d0221d1a9 100644
--- a/glide.yaml
+++ b/glide.yaml
@@ -18,7 +18,7 @@ import:
 - package: github.com/spf13/viper
   version: v1.0.0
 - package: github.com/tendermint/abci
-  version: 22b491bb1952125dd2fb0730d6ca8e59e310547c
+  version: develop
   subpackages:
   - client
   - example/dummy
@@ -55,7 +55,7 @@ import:
   subpackages:
   - context
 - package: google.golang.org/grpc
-  version: v1.7.0
+  version: v1.7.3
 testImport:
 - package: github.com/go-kit/kit
   subpackages:
diff --git a/mempool/mempool.go b/mempool/mempool.go
index 44a6ab0d6..ccd615ac2 100644
--- a/mempool/mempool.go
+++ b/mempool/mempool.go
@@ -3,6 +3,7 @@ package mempool
 import (
 	"bytes"
 	"container/list"
+	"fmt"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -191,17 +192,7 @@ func (mem *Mempool) CheckTx(tx types.Tx, cb func(*abci.Response)) (err error) {
 
 	// CACHE
 	if mem.cache.Exists(tx) {
-		if cb != nil {
-			cb(&abci.Response{
-				Value: &abci.Response_CheckTx{
-					&abci.ResponseCheckTx{
-						Code: abci.CodeType_BadNonce, // TODO or duplicate tx
-						Log:  "Duplicate transaction (ignored)",
-					},
-				},
-			})
-		}
-		return nil // TODO: return an error (?)
+		return fmt.Errorf("Tx already exists in cache")
 	}
 	mem.cache.Push(tx)
 	// END CACHE
@@ -245,7 +236,7 @@ func (mem *Mempool) resCbNormal(req *abci.Request, res *abci.Response) {
 	switch r := res.Value.(type) {
 	case *abci.Response_CheckTx:
 		tx := req.GetCheckTx().Tx
-		if r.CheckTx.Code == abci.CodeType_OK {
+		if r.CheckTx.Code == abci.CodeTypeOK {
 			mem.counter++
 			memTx := &mempoolTx{
 				counter: mem.counter,
@@ -277,7 +268,7 @@ func (mem *Mempool) resCbRecheck(req *abci.Request, res *abci.Response) {
 			cmn.PanicSanity(cmn.Fmt("Unexpected tx response from proxy during recheck\n"+
 				"Expected %X, got %X", r.CheckTx.Data, memTx.tx))
 		}
-		if r.CheckTx.Code == abci.CodeType_OK {
+		if r.CheckTx.Code == abci.CodeTypeOK {
 			// Good, nothing to do.
 		} else {
 			// Tx became invalidated due to newly committed block.
diff --git a/mempool/mempool_test.go b/mempool/mempool_test.go
index 22caee27d..4d75cc58d 100644
--- a/mempool/mempool_test.go
+++ b/mempool/mempool_test.go
@@ -14,6 +14,7 @@ import (
 	"github.com/tendermint/abci/example/counter"
 	"github.com/tendermint/abci/example/dummy"
 	abci "github.com/tendermint/abci/types"
+	cmn "github.com/tendermint/tmlibs/common"
 	"github.com/tendermint/tmlibs/log"
 
 	cfg "github.com/tendermint/tendermint/config"
@@ -122,10 +123,10 @@ func TestSerialReap(t *testing.T) {
 	mempool := newMempoolWithApp(cc)
 	appConnCon, _ := cc.NewABCIClient()
 	appConnCon.SetLogger(log.TestingLogger().With("module", "abci-client", "connection", "consensus"))
-	if err := appConnCon.Start(); err != nil {
-		t.Fatalf("Error starting ABCI client: %v", err.Error())
-	}
+	err := appConnCon.Start()
+	require.Nil(t, err)
 
+	cacheMap := make(map[string]struct{})
 	deliverTxsRange := func(start, end int) {
 		// Deliver some txs.
 		for i := start; i < end; i++ {
@@ -134,26 +135,23 @@ func TestSerialReap(t *testing.T) {
 			txBytes := make([]byte, 8)
 			binary.BigEndian.PutUint64(txBytes, uint64(i))
 			err := mempool.CheckTx(txBytes, nil)
-			if err != nil {
-				t.Fatalf("Error after CheckTx: %v", err)
+			_, cached := cacheMap[string(txBytes)]
+			if cached {
+				require.NotNil(t, err, "expected error for cached tx")
+			} else {
+				require.Nil(t, err, "expected no err for uncached tx")
 			}
+			cacheMap[string(txBytes)] = struct{}{}
 
-			// This will fail because not serial (incrementing)
-			// However, error should still be nil.
-			// It just won't show up on Reap().
+			// Duplicates are cached and should return error
 			err = mempool.CheckTx(txBytes, nil)
-			if err != nil {
-				t.Fatalf("Error after CheckTx: %v", err)
-			}
-
+			require.NotNil(t, err, "Expected error after CheckTx on duplicated tx")
 		}
 	}
 
 	reapCheck := func(exp int) {
 		txs := mempool.Reap(-1)
-		if len(txs) != exp {
-			t.Fatalf("Expected to reap %v txs but got %v", exp, len(txs))
-		}
+		require.Equal(t, len(txs), exp, cmn.Fmt("Expected to reap %v txs but got %v", exp, len(txs)))
 	}
 
 	updateRange := func(start, end int) {
diff --git a/node/node.go b/node/node.go
index 7841a103d..eb5509717 100644
--- a/node/node.go
+++ b/node/node.go
@@ -256,20 +256,20 @@ func NewNode(config *cfg.Config,
 			if err != nil {
 				return err
 			}
-			if resQuery.Code.IsOK() {
-				return nil
+			if resQuery.IsErr() {
+				return resQuery
 			}
-			return errors.New(resQuery.Code.String())
+			return nil
 		})
 		sw.SetPubKeyFilter(func(pubkey crypto.PubKeyEd25519) error {
 			resQuery, err := proxyApp.Query().QuerySync(abci.RequestQuery{Path: cmn.Fmt("/p2p/filter/pubkey/%X", pubkey.Bytes())})
 			if err != nil {
 				return err
 			}
-			if resQuery.Code.IsOK() {
-				return nil
+			if resQuery.IsErr() {
+				return resQuery
 			}
-			return errors.New(resQuery.Code.String())
+			return nil
 		})
 	}
 
diff --git a/rpc/client/event_test.go b/rpc/client/event_test.go
index 58f43c224..40a42c186 100644
--- a/rpc/client/event_test.go
+++ b/rpc/client/event_test.go
@@ -6,6 +6,7 @@ import (
 
 	"github.com/stretchr/testify/require"
 
+	abci "github.com/tendermint/abci/types"
 	cmn "github.com/tendermint/tmlibs/common"
 
 	"github.com/tendermint/tendermint/rpc/client"
@@ -90,7 +91,7 @@ func TestTxEventsSentWithBroadcastTxAsync(t *testing.T) {
 		// send async
 		txres, err := c.BroadcastTxAsync(tx)
 		require.Nil(err, "%+v", err)
-		require.True(txres.Code.IsOK())
+		require.Equal(txres.Code, abci.CodeTypeOK) // FIXME
 
 		// and wait for confirmation
 		evt, err := client.WaitForOneEvent(c, evtTyp, waitForEventTimeout)
@@ -100,7 +101,7 @@ func TestTxEventsSentWithBroadcastTxAsync(t *testing.T) {
 		require.True(ok, "%d: %#v", i, evt)
 		// make sure this is the proper tx
 		require.EqualValues(tx, txe.Tx)
-		require.True(txe.Result.Code.IsOK())
+		require.True(txe.Result.IsOK())
 	}
 }
 
@@ -122,7 +123,7 @@ func TestTxEventsSentWithBroadcastTxSync(t *testing.T) {
 		// send sync
 		txres, err := c.BroadcastTxSync(tx)
 		require.Nil(err, "%+v", err)
-		require.True(txres.Code.IsOK())
+		require.Equal(txres.Code, abci.CodeTypeOK) // FIXME
 
 		// and wait for confirmation
 		evt, err := client.WaitForOneEvent(c, evtTyp, waitForEventTimeout)
@@ -132,6 +133,6 @@ func TestTxEventsSentWithBroadcastTxSync(t *testing.T) {
 		require.True(ok, "%d: %#v", i, evt)
 		// make sure this is the proper tx
 		require.EqualValues(tx, txe.Tx)
-		require.True(txe.Result.Code.IsOK())
+		require.True(txe.Result.IsOK())
 	}
 }
diff --git a/rpc/client/mock/abci.go b/rpc/client/mock/abci.go
index 2ffa9269d..ad528efc7 100644
--- a/rpc/client/mock/abci.go
+++ b/rpc/client/mock/abci.go
@@ -32,7 +32,7 @@ func (a ABCIApp) ABCIQuery(path string, data data.Bytes) (*ctypes.ResultABCIQuer
 
 func (a ABCIApp) ABCIQueryWithOptions(path string, data data.Bytes, opts client.ABCIQueryOptions) (*ctypes.ResultABCIQuery, error) {
 	q := a.App.Query(abci.RequestQuery{data, path, opts.Height, opts.Trusted})
-	return &ctypes.ResultABCIQuery{q.Result()}, nil
+	return &ctypes.ResultABCIQuery{&q}, nil
 }
 
 func (a ABCIApp) BroadcastTxCommit(tx types.Tx) (*ctypes.ResultBroadcastTxCommit, error) {
@@ -91,7 +91,7 @@ func (m ABCIMock) ABCIQueryWithOptions(path string, data data.Bytes, opts client
 		return nil, err
 	}
 	resQuery := res.(abci.ResponseQuery)
-	return &ctypes.ResultABCIQuery{resQuery.Result()}, nil
+	return &ctypes.ResultABCIQuery{&resQuery}, nil
 }
 
 func (m ABCIMock) BroadcastTxCommit(tx types.Tx) (*ctypes.ResultBroadcastTxCommit, error) {
@@ -135,7 +135,7 @@ func NewABCIRecorder(client client.ABCIClient) *ABCIRecorder {
 type QueryArgs struct {
 	Path    string
 	Data    data.Bytes
-	Height  uint64
+	Height  int64
 	Trusted bool
 }
 
diff --git a/rpc/client/mock/abci_test.go b/rpc/client/mock/abci_test.go
index 216bd7c2b..773297c8c 100644
--- a/rpc/client/mock/abci_test.go
+++ b/rpc/client/mock/abci_test.go
@@ -22,7 +22,7 @@ func TestABCIMock(t *testing.T) {
 	assert, require := assert.New(t), require.New(t)
 
 	key, value := []byte("foo"), []byte("bar")
-	height := uint64(10)
+	height := int64(10)
 	goodTx := types.Tx{0x01, 0xff}
 	badTx := types.Tx{0x12, 0x21}
 
@@ -168,9 +168,9 @@ func TestABCIApp(t *testing.T) {
 	tx := fmt.Sprintf("%s=%s", key, value)
 	res, err := m.BroadcastTxCommit(types.Tx(tx))
 	require.Nil(err)
-	assert.True(res.CheckTx.Code.IsOK())
+	assert.True(res.CheckTx.IsOK())
 	require.NotNil(res.DeliverTx)
-	assert.True(res.DeliverTx.Code.IsOK())
+	assert.True(res.DeliverTx.IsOK())
 
 	// check the key
 	qres, err := m.ABCIQueryWithOptions("/key", data.Bytes(key), client.ABCIQueryOptions{Trusted: true})
diff --git a/rpc/client/rpc_test.go b/rpc/client/rpc_test.go
index 63a742ab7..06183b9fd 100644
--- a/rpc/client/rpc_test.go
+++ b/rpc/client/rpc_test.go
@@ -8,7 +8,9 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	abci "github.com/tendermint/abci/types"
 	"github.com/tendermint/iavl"
+
 	"github.com/tendermint/tendermint/rpc/client"
 	rpctest "github.com/tendermint/tendermint/rpc/test"
 	"github.com/tendermint/tendermint/types"
@@ -110,7 +112,7 @@ func TestABCIQuery(t *testing.T) {
 		// wait before querying
 		client.WaitForHeight(c, apph, nil)
 		qres, err := c.ABCIQuery("/key", k)
-		if assert.Nil(t, err) && assert.True(t, qres.Code.IsOK()) {
+		if assert.Nil(t, err) && assert.True(t, qres.IsOK()) {
 			assert.EqualValues(t, v, qres.Value)
 		}
 	}
@@ -136,7 +138,7 @@ func TestAppCalls(t *testing.T) {
 		k, v, tx := MakeTxKV()
 		bres, err := c.BroadcastTxCommit(tx)
 		require.Nil(err, "%d: %+v", i, err)
-		require.True(bres.DeliverTx.Code.IsOK())
+		require.True(bres.DeliverTx.IsOK())
 		txh := bres.Height
 		apph := txh + 1 // this is where the tx will be applied to the state
 
@@ -145,7 +147,7 @@ func TestAppCalls(t *testing.T) {
 			t.Error(err)
 		}
 		qres, err := c.ABCIQueryWithOptions("/key", k, client.ABCIQueryOptions{Trusted: true})
-		if assert.Nil(err) && assert.True(qres.Code.IsOK()) {
+		if assert.Nil(err) && assert.True(qres.IsOK()) {
 			// assert.Equal(k, data.GetKey())  // only returned for proofs
 			assert.EqualValues(v, qres.Value)
 		}
@@ -193,7 +195,7 @@ func TestAppCalls(t *testing.T) {
 
 		// and we got a proof that works!
 		pres, err := c.ABCIQueryWithOptions("/key", k, client.ABCIQueryOptions{Trusted: false})
-		if assert.Nil(err) && assert.True(pres.Code.IsOK()) {
+		if assert.Nil(err) && assert.True(pres.IsOK()) {
 			proof, err := iavl.ReadKeyExistsProof(pres.Proof)
 			if assert.Nil(err) {
 				key := pres.Key
@@ -216,7 +218,7 @@ func TestBroadcastTxSync(t *testing.T) {
 		_, _, tx := MakeTxKV()
 		bres, err := c.BroadcastTxSync(tx)
 		require.Nil(err, "%d: %+v", i, err)
-		require.True(bres.Code.IsOK())
+		require.Equal(bres.Code, abci.CodeTypeOK) // FIXME
 
 		require.Equal(initMempoolSize+1, mempool.Size())
 
@@ -234,8 +236,8 @@ func TestBroadcastTxCommit(t *testing.T) {
 		_, _, tx := MakeTxKV()
 		bres, err := c.BroadcastTxCommit(tx)
 		require.Nil(err, "%d: %+v", i, err)
-		require.True(bres.CheckTx.Code.IsOK())
-		require.True(bres.DeliverTx.Code.IsOK())
+		require.True(bres.CheckTx.IsOK())
+		require.True(bres.DeliverTx.IsOK())
 
 		require.Equal(0, mempool.Size())
 	}
@@ -284,7 +286,7 @@ func TestTx(t *testing.T) {
 				assert.EqualValues(txHeight, ptx.Height)
 				assert.EqualValues(tx, ptx.Tx)
 				assert.Zero(ptx.Index)
-				assert.True(ptx.TxResult.Code.IsOK())
+				assert.True(ptx.TxResult.IsOK())
 
 				// time to verify the proof
 				proof := ptx.Proof
@@ -321,7 +323,7 @@ func TestTxSearch(t *testing.T) {
 		assert.EqualValues(t, txHeight, ptx.Height)
 		assert.EqualValues(t, tx, ptx.Tx)
 		assert.Zero(t, ptx.Index)
-		assert.True(t, ptx.TxResult.Code.IsOK())
+		assert.True(t, ptx.TxResult.IsOK())
 
 		// time to verify the proof
 		proof := ptx.Proof
diff --git a/rpc/client/types.go b/rpc/client/types.go
index dc573edd6..89bd2f98c 100644
--- a/rpc/client/types.go
+++ b/rpc/client/types.go
@@ -3,7 +3,7 @@ package client
 // ABCIQueryOptions can be used to provide options for ABCIQuery call other
 // than the DefaultABCIQueryOptions.
 type ABCIQueryOptions struct {
-	Height  uint64
+	Height  int64
 	Trusted bool
 }
 
diff --git a/rpc/core/abci.go b/rpc/core/abci.go
index a64c3d297..2fe7214a4 100644
--- a/rpc/core/abci.go
+++ b/rpc/core/abci.go
@@ -45,9 +45,9 @@ import (
 // |-----------+--------+---------+----------+------------------------------------------------|
 // | path      | string | false   | false    | Path to the data ("/a/b/c")                    |
 // | data      | []byte | false   | true     | Data                                           |
-// | height    | uint64 | 0       | false    | Height (0 means latest)                        |
+// | height    | int64 | 0       | false    | Height (0 means latest)                        |
 // | trusted   | bool   | false   | false    | Does not include a proof of the data inclusion |
-func ABCIQuery(path string, data data.Bytes, height uint64, trusted bool) (*ctypes.ResultABCIQuery, error) {
+func ABCIQuery(path string, data data.Bytes, height int64, trusted bool) (*ctypes.ResultABCIQuery, error) {
 	resQuery, err := proxyAppQuery.QuerySync(abci.RequestQuery{
 		Path:   path,
 		Data:   data,
@@ -59,7 +59,7 @@ func ABCIQuery(path string, data data.Bytes, height uint64, trusted bool) (*ctyp
 	}
 	logger.Info("ABCIQuery", "path", path, "data", data, "result", resQuery)
 	return &ctypes.ResultABCIQuery{
-		resQuery.Result(),
+		resQuery,
 	}, nil
 }
 
diff --git a/rpc/core/mempool.go b/rpc/core/mempool.go
index c2e5d2f9b..3f663c376 100644
--- a/rpc/core/mempool.go
+++ b/rpc/core/mempool.go
@@ -174,7 +174,7 @@ func BroadcastTxCommit(tx types.Tx) (*ctypes.ResultBroadcastTxCommit, error) {
 	}
 	checkTxRes := <-checkTxResCh
 	checkTxR := checkTxRes.GetCheckTx()
-	if checkTxR.Code != abci.CodeType_OK {
+	if checkTxR.Code != abci.CodeTypeOK {
 		// CheckTx failed!
 		return &ctypes.ResultBroadcastTxCommit{
 			CheckTx:   *checkTxR,
diff --git a/rpc/core/types/responses.go b/rpc/core/types/responses.go
index 18c9e8e7f..2a7e729e9 100644
--- a/rpc/core/types/responses.go
+++ b/rpc/core/types/responses.go
@@ -96,9 +96,9 @@ type ResultDumpConsensusState struct {
 }
 
 type ResultBroadcastTx struct {
-	Code abci.CodeType `json:"code"`
-	Data data.Bytes    `json:"data"`
-	Log  string        `json:"log"`
+	Code uint32     `json:"code"`
+	Data data.Bytes `json:"data"`
+	Log  string     `json:"log"`
 
 	Hash data.Bytes `json:"hash"`
 }
@@ -128,7 +128,7 @@ type ResultABCIInfo struct {
 }
 
 type ResultABCIQuery struct {
-	*abci.ResultQuery `json:"response"`
+	*abci.ResponseQuery `json:"response"`
 }
 
 type ResultUnsafeFlushMempool struct{}
diff --git a/state/execution.go b/state/execution.go
index c67f90076..1905b62f5 100644
--- a/state/execution.go
+++ b/state/execution.go
@@ -54,7 +54,7 @@ func execBlockOnProxyApp(txEventPublisher types.TxEventPublisher, proxyAppConn p
 			// Blocks may include invalid txs.
 			// reqDeliverTx := req.(abci.RequestDeliverTx)
 			txResult := r.DeliverTx
-			if txResult.Code == abci.CodeType_OK {
+			if txResult.Code == abci.CodeTypeOK {
 				validTxs++
 			} else {
 				logger.Debug("Invalid tx", "code", txResult.Code, "log", txResult.Log)
@@ -80,6 +80,8 @@ func execBlockOnProxyApp(txEventPublisher types.TxEventPublisher, proxyAppConn p
 	_, err := proxyAppConn.BeginBlockSync(abci.RequestBeginBlock{
 		block.Hash(),
 		types.TM2PB.Header(block.Header),
+		nil,
+		nil,
 	})
 	if err != nil {
 		logger.Error("Error in proxyAppConn.BeginBlock", "err", err)
@@ -95,7 +97,7 @@ func execBlockOnProxyApp(txEventPublisher types.TxEventPublisher, proxyAppConn p
 	}
 
 	// End block
-	abciResponses.EndBlock, err = proxyAppConn.EndBlockSync(abci.RequestEndBlock{uint64(block.Height)})
+	abciResponses.EndBlock, err = proxyAppConn.EndBlockSync(abci.RequestEndBlock{block.Height})
 	if err != nil {
 		logger.Error("Error in proxyAppConn.EndBlock", "err", err)
 		return nil, err
diff --git a/state/txindex/kv/kv.go b/state/txindex/kv/kv.go
index 5ca4d0628..d40fe80fe 100644
--- a/state/txindex/kv/kv.go
+++ b/state/txindex/kv/kv.go
@@ -211,10 +211,10 @@ func lookForHash(conditions []query.Condition) (hash []byte, err error, ok bool)
 	return
 }
 
-func lookForHeight(conditions []query.Condition) (height uint64, index int) {
+func lookForHeight(conditions []query.Condition) (height int64, index int) {
 	for i, c := range conditions {
 		if c.Tag == types.TxHeightKey {
-			return uint64(c.Operand.(int64)), i
+			return c.Operand.(int64), i
 		}
 	}
 	return 0, -1
@@ -330,7 +330,7 @@ LOOP:
 ///////////////////////////////////////////////////////////////////////////////
 // Keys
 
-func startKey(c query.Condition, height uint64) []byte {
+func startKey(c query.Condition, height int64) []byte {
 	var key string
 	if height > 0 {
 		key = fmt.Sprintf("%s/%v/%d", c.Tag, c.Operand, height)
@@ -340,7 +340,7 @@ func startKey(c query.Condition, height uint64) []byte {
 	return []byte(key)
 }
 
-func startKeyForRange(r queryRange, height uint64) []byte {
+func startKeyForRange(r queryRange, height int64) []byte {
 	if r.lowerBound == nil {
 		return []byte(fmt.Sprintf("%s", r.key))
 	}
diff --git a/state/txindex/kv/kv_test.go b/state/txindex/kv/kv_test.go
index efe17a182..0eac17607 100644
--- a/state/txindex/kv/kv_test.go
+++ b/state/txindex/kv/kv_test.go
@@ -19,7 +19,7 @@ func TestTxIndex(t *testing.T) {
 	indexer := NewTxIndex(db.NewMemDB())
 
 	tx := types.Tx("HELLO WORLD")
-	txResult := &types.TxResult{1, 0, tx, abci.ResponseDeliverTx{Data: []byte{0}, Code: abci.CodeType_OK, Log: "", Tags: []*abci.KVPair{}}}
+	txResult := &types.TxResult{1, 0, tx, abci.ResponseDeliverTx{Data: []byte{0}, Code: abci.CodeTypeOK, Log: "", Tags: []*abci.KVPair{}}}
 	hash := tx.Hash()
 
 	batch := txindex.NewBatch(1)
@@ -34,7 +34,7 @@ func TestTxIndex(t *testing.T) {
 	assert.Equal(t, txResult, loadedTxResult)
 
 	tx2 := types.Tx("BYE BYE WORLD")
-	txResult2 := &types.TxResult{1, 0, tx2, abci.ResponseDeliverTx{Data: []byte{0}, Code: abci.CodeType_OK, Log: "", Tags: []*abci.KVPair{}}}
+	txResult2 := &types.TxResult{1, 0, tx2, abci.ResponseDeliverTx{Data: []byte{0}, Code: abci.CodeTypeOK, Log: "", Tags: []*abci.KVPair{}}}
 	hash2 := tx2.Hash()
 
 	err = indexer.Index(txResult2)
@@ -145,12 +145,12 @@ func TestIndexAllTags(t *testing.T) {
 
 func txResultWithTags(tags []*abci.KVPair) *types.TxResult {
 	tx := types.Tx("HELLO WORLD")
-	return &types.TxResult{1, 0, tx, abci.ResponseDeliverTx{Data: []byte{0}, Code: abci.CodeType_OK, Log: "", Tags: tags}}
+	return &types.TxResult{1, 0, tx, abci.ResponseDeliverTx{Data: []byte{0}, Code: abci.CodeTypeOK, Log: "", Tags: tags}}
 }
 
 func benchmarkTxIndex(txsCount int, b *testing.B) {
 	tx := types.Tx("HELLO WORLD")
-	txResult := &types.TxResult{1, 0, tx, abci.ResponseDeliverTx{Data: []byte{0}, Code: abci.CodeType_OK, Log: "", Tags: []*abci.KVPair{}}}
+	txResult := &types.TxResult{1, 0, tx, abci.ResponseDeliverTx{Data: []byte{0}, Code: abci.CodeTypeOK, Log: "", Tags: []*abci.KVPair{}}}
 
 	dir, err := ioutil.TempDir("", "tx_index_db")
 	if err != nil {
diff --git a/test/app/counter_test.sh b/test/app/counter_test.sh
index 0198f85cd..22a3ddb88 100644
--- a/test/app/counter_test.sh
+++ b/test/app/counter_test.sh
@@ -14,20 +14,41 @@ TESTNAME=$1
 # Send some txs
 
 function getCode() {
+	set +u
 	R=$1
-	if [[ "$R" == "{}" ]]; then
+	set -u
+	if [[ "$R" == "" ]]; then
+		echo -1
+	fi
+
+	if [[ $(echo $R | jq 'has("code")') == "true" ]]; then
+		# this wont actually work if theres an error ...
+		echo "$R" | jq ".code"
+	else
 		# protobuf auto adds `omitempty` to everything so code OK and empty data/log
 		# will not even show when marshalled into json
 		# apparently we can use github.com/golang/protobuf/jsonpb to do the marshalling ...
 		echo 0
-	else
-		# this wont actually work if theres an error ...
-		echo "$R" | jq .code
 	fi
 }
 
+# build grpc client if needed
+if [[ "$GRPC_BROADCAST_TX" != "" ]]; then
+	if [  -f grpc_client ]; then
+		rm grpc_client
+	fi
+	echo "... building grpc_client"
+	go build -o grpc_client grpc_client.go
+fi
+
 function sendTx() {
 	TX=$1
+	set +u
+	SHOULD_ERR=$2
+	if [ "$SHOULD_ERR" == "" ]; then
+		SHOULD_ERR=false
+	fi
+	set -u
 	if [[ "$GRPC_BROADCAST_TX" == "" ]]; then
 		RESPONSE=$(curl -s localhost:46657/broadcast_tx_commit?tx=0x"$TX")
 		IS_ERR=$(echo "$RESPONSE" | jq 'has("error")')
@@ -36,11 +57,6 @@ function sendTx() {
 
 		RESPONSE=$(echo "$RESPONSE" | jq '.result')
 	else
-	 	if [  -f grpc_client ]; then
-			rm grpc_client
-	     	fi
-		echo "... building grpc_client"
-		go build -o grpc_client grpc_client.go
 		RESPONSE=$(./grpc_client "$TX")
 		IS_ERR=false
 		ERROR=""
@@ -64,11 +80,20 @@ function sendTx() {
 	echo "TX $TX"
 	echo "RESPONSE $RESPONSE"
 	echo "ERROR $ERROR"
+	echo "IS_ERR $IS_ERR"
 	echo "----"
 
-	if $IS_ERR; then
-		echo "Unexpected error sending tx ($TX): $ERROR"
-		exit 1
+	if $SHOULD_ERR; then
+		if [[ "$IS_ERR" != "true" ]]; then
+			echo "Expected error sending tx ($TX)"
+			exit 1
+		fi
+	else
+		if [[ "$IS_ERR" == "true" ]]; then
+			echo "Unexpected error sending tx ($TX)"
+			exit 1
+		fi
+
 	fi
 }
 
@@ -86,12 +111,7 @@ fi
 echo "... sending tx. expect error"
 
 # second time should get rejected by the mempool (return error and non-zero code)
-sendTx $TX
-echo "CHECKTX CODE: $CHECK_TX_CODE"
-if [[ "$CHECK_TX_CODE" == 0 ]]; then
-	echo "Got zero exit code for $TX. Expected tx to be rejected by mempool. $RESPONSE"
-	exit 1
-fi
+sendTx $TX true
 
 
 echo "... sending tx. expect no error"
diff --git a/types/protobuf.go b/types/protobuf.go
index c8c9f8434..c97b53872 100644
--- a/types/protobuf.go
+++ b/types/protobuf.go
@@ -13,9 +13,9 @@ type tm2pb struct{}
 func (tm2pb) Header(header *Header) *types.Header {
 	return &types.Header{
 		ChainId:        header.ChainID,
-		Height:         uint64(header.Height),
-		Time:           uint64(header.Time.Unix()),
-		NumTxs:         uint64(header.NumTxs),
+		Height:         header.Height,
+		Time:           header.Time.Unix(),
+		NumTxs:         int32(header.NumTxs), // XXX: overflow
 		LastBlockId:    TM2PB.BlockID(header.LastBlockID),
 		LastCommitHash: header.LastCommitHash,
 		DataHash:       header.DataHash,
@@ -32,7 +32,7 @@ func (tm2pb) BlockID(blockID BlockID) *types.BlockID {
 
 func (tm2pb) PartSetHeader(partSetHeader PartSetHeader) *types.PartSetHeader {
 	return &types.PartSetHeader{
-		Total: uint64(partSetHeader.Total),
+		Total: int32(partSetHeader.Total), // XXX: overflow
 		Hash:  partSetHeader.Hash,
 	}
 }
@@ -40,7 +40,7 @@ func (tm2pb) PartSetHeader(partSetHeader PartSetHeader) *types.PartSetHeader {
 func (tm2pb) Validator(val *Validator) *types.Validator {
 	return &types.Validator{
 		PubKey: val.PubKey.Bytes(),
-		Power:  uint64(val.VotingPower),
+		Power:  val.VotingPower,
 	}
 }