diff --git a/example/dummy/dummy.go b/example/dummy/dummy.go
index 5db71f96c..82927ca6e 100644
--- a/example/dummy/dummy.go
+++ b/example/dummy/dummy.go
@@ -4,19 +4,20 @@ import (
 	"strings"
 
 	"github.com/tendermint/abci/types"
-	"github.com/tendermint/merkleeyes/iavl"
+	wire "github.com/tendermint/go-wire"
+	"github.com/tendermint/iavl"
 	cmn "github.com/tendermint/tmlibs/common"
-	"github.com/tendermint/tmlibs/merkle"
+	dbm "github.com/tendermint/tmlibs/db"
 )
 
 type DummyApplication struct {
 	types.BaseApplication
 
-	state merkle.Tree
+	state *iavl.VersionedTree
 }
 
 func NewDummyApplication() *DummyApplication {
-	state := iavl.NewIAVLTree(0, nil)
+	state := iavl.NewVersionedTree(0, dbm.NewMemDB())
 	return &DummyApplication{state: state}
 }
 
@@ -46,22 +47,26 @@ func (app *DummyApplication) Commit() types.Result {
 
 func (app *DummyApplication) Query(reqQuery types.RequestQuery) (resQuery types.ResponseQuery) {
 	if reqQuery.Prove {
-		value, proof, exists := app.state.Proof(reqQuery.Data)
+		value, proof, err := app.state.GetWithProof(reqQuery.Data)
+		// be stupid here
+		if err != nil {
+			panic(err)
+		}
 		resQuery.Index = -1 // TODO make Proof return index
 		resQuery.Key = reqQuery.Data
 		resQuery.Value = value
-		resQuery.Proof = proof
-		if exists {
+		resQuery.Proof = wire.BinaryBytes(proof)
+		if value == nil {
 			resQuery.Log = "exists"
 		} else {
 			resQuery.Log = "does not exist"
 		}
 		return
 	} else {
-		index, value, exists := app.state.Get(reqQuery.Data)
+		index, value := app.state.Get(reqQuery.Data)
 		resQuery.Index = int64(index)
 		resQuery.Value = value
-		if exists {
+		if value != nil {
 			resQuery.Log = "exists"
 		} else {
 			resQuery.Log = "does not exist"
diff --git a/example/dummy/dummy_test.go b/example/dummy/dummy_test.go
index fa9d531b7..41e033bc0 100644
--- a/example/dummy/dummy_test.go
+++ b/example/dummy/dummy_test.go
@@ -11,7 +11,7 @@ import (
 	"github.com/tendermint/abci/server"
 	"github.com/tendermint/abci/types"
 	crypto "github.com/tendermint/go-crypto"
-	"github.com/tendermint/merkleeyes/iavl"
+	"github.com/tendermint/iavl"
 	cmn "github.com/tendermint/tmlibs/common"
 	"github.com/tendermint/tmlibs/log"
 )
@@ -39,9 +39,10 @@ func testDummy(t *testing.T, app types.Application, tx []byte, key, value string
 	})
 	require.Equal(t, types.CodeType_OK, resQuery.Code)
 	require.Equal(t, value, string(resQuery.Value))
-	proof, err := iavl.ReadProof(resQuery.Proof)
+	proof, err := iavl.ReadKeyExistsProof(resQuery.Proof)
 	require.Nil(t, err)
-	require.True(t, proof.Verify([]byte(key), resQuery.Value, proof.RootHash)) // NOTE: we have no way to verify the RootHash
+	err = proof.Verify([]byte(key), resQuery.Value, proof.RootHash)
+	require.Nil(t, err, "%+v", err) // NOTE: we have no way to verify the RootHash
 }
 
 func TestDummyKV(t *testing.T) {
@@ -309,7 +310,8 @@ func testClient(t *testing.T, app abcicli.Client, tx []byte, key, value string)
 	require.Nil(t, err)
 	require.Equal(t, types.CodeType_OK, resQuery.Code)
 	require.Equal(t, value, string(resQuery.Value))
-	proof, err := iavl.ReadProof(resQuery.Proof)
+	proof, err := iavl.ReadKeyExistsProof(resQuery.Proof)
 	require.Nil(t, err)
-	require.True(t, proof.Verify([]byte(key), resQuery.Value, proof.RootHash)) // NOTE: we have no way to verify the RootHash
+	err = proof.Verify([]byte(key), resQuery.Value, proof.RootHash)
+	require.Nil(t, err, "%+v", err) // NOTE: we have no way to verify the RootHash
 }
diff --git a/example/dummy/persistent_dummy.go b/example/dummy/persistent_dummy.go
index a8bfbcf02..89bc6e721 100644
--- a/example/dummy/persistent_dummy.go
+++ b/example/dummy/persistent_dummy.go
@@ -3,13 +3,12 @@ package dummy
 import (
 	"bytes"
 	"encoding/hex"
+	"path"
 	"strconv"
 	"strings"
 
-	"github.com/pkg/errors"
 	"github.com/tendermint/abci/types"
-	wire "github.com/tendermint/go-wire"
-	"github.com/tendermint/merkleeyes/iavl"
+	"github.com/tendermint/iavl"
 	cmn "github.com/tendermint/tmlibs/common"
 	dbm "github.com/tendermint/tmlibs/db"
 	"github.com/tendermint/tmlibs/log"
@@ -23,11 +22,11 @@ const (
 
 type PersistentDummyApplication struct {
 	app *DummyApplication
-	db  dbm.DB
 
 	// latest received
 	// TODO: move to merkle tree?
 	blockHeader *types.Header
+	height      uint64
 
 	// validator set
 	changes []*types.Validator
@@ -36,17 +35,22 @@ type PersistentDummyApplication struct {
 }
 
 func NewPersistentDummyApplication(dbDir string) *PersistentDummyApplication {
-	db := dbm.NewDB("dummy", "leveldb", dbDir)
-	lastBlock := LoadLastBlock(db)
+	name := "dummy"
+	dbPath := path.Join(dbDir, name+".db")
+	empty, _ := cmn.IsDirEmpty(dbPath)
 
-	stateTree := iavl.NewIAVLTree(0, db)
-	stateTree.Load(lastBlock.AppHash)
+	db, err := dbm.NewGoLevelDB(name, dbDir)
+	if err != nil {
+		panic(err)
+	}
 
-	// log.Notice("Loaded state", "block", lastBlock.Height, "root", stateTree.Hash())
+	stateTree := iavl.NewVersionedTree(500, db)
+	if !empty {
+		stateTree.Load()
+	}
 
 	return &PersistentDummyApplication{
 		app:    &DummyApplication{state: stateTree},
-		db:     db,
 		logger: log.NewNopLogger(),
 	}
 }
@@ -57,9 +61,8 @@ func (app *PersistentDummyApplication) SetLogger(l log.Logger) {
 
 func (app *PersistentDummyApplication) Info(req types.RequestInfo) (resInfo types.ResponseInfo) {
 	resInfo = app.app.Info(req)
-	lastBlock := LoadLastBlock(app.db)
-	resInfo.LastBlockHeight = lastBlock.Height
-	resInfo.LastBlockAppHash = lastBlock.AppHash
+	resInfo.LastBlockHeight = app.height
+	resInfo.LastBlockAppHash = app.app.state.Hash()
 	return resInfo
 }
 
@@ -86,18 +89,26 @@ func (app *PersistentDummyApplication) CheckTx(tx []byte) types.Result {
 }
 
 func (app *PersistentDummyApplication) Commit() types.Result {
-	// Save
-	appHash := app.app.state.Save()
-	app.logger.Info("Saved state", "root", appHash)
+	app.height = app.blockHeader.Height
+
+	// Save a new version
+	var appHash []byte
+	var err error
+	if app.app.state.Size() > 0 {
+		appHash, err = app.app.state.SaveVersion(app.height)
+		if err != nil {
+			// if this wasn't a dummy app, we'd do something smarter
+			panic(err)
+		}
+		app.logger.Info("Saved state", "root", appHash)
+	}
 
 	lastBlock := LastBlockInfo{
-		Height:  app.blockHeader.Height,
+		Height:  app.height,
 		AppHash: appHash, // this hash will be in the next block header
 	}
 
 	app.logger.Info("Saving block", "height", lastBlock.Height, "root", lastBlock.AppHash)
-	SaveLastBlock(app.db, lastBlock)
-
 	return types.NewResultOK(appHash, "")
 }
 
@@ -139,31 +150,6 @@ type LastBlockInfo struct {
 	AppHash []byte
 }
 
-// Get the last block from the db
-func LoadLastBlock(db dbm.DB) (lastBlock LastBlockInfo) {
-	buf := db.Get(lastBlockKey)
-	if len(buf) != 0 {
-		r, n, err := bytes.NewReader(buf), new(int), new(error)
-		wire.ReadBinaryPtr(&lastBlock, r, 0, n, err)
-		if *err != nil {
-			cmn.PanicCrisis(errors.Wrap(*err, "cannot load last block (data has been corrupted or its spec has changed)"))
-		}
-		// TODO: ensure that buf is completely read.
-	}
-
-	return lastBlock
-}
-
-func SaveLastBlock(db dbm.DB, lastBlock LastBlockInfo) {
-	buf, n, err := new(bytes.Buffer), new(int), new(error)
-	wire.WriteBinary(lastBlock, buf, n, err)
-	if *err != nil {
-		// TODO
-		cmn.PanicCrisis(errors.Wrap(*err, "cannot save last block"))
-	}
-	db.Set(lastBlockKey, buf.Bytes())
-}
-
 //---------------------------------------------
 // update validators
 
diff --git a/glide.lock b/glide.lock
index 7b79f0e55..d2dfc9a68 100644
--- a/glide.lock
+++ b/glide.lock
@@ -1,5 +1,5 @@
-hash: f9c2ddad16bf8652076a93bd9f398bb498eefb2f5bd2c89a77d966ebd12feec8
-updated: 2017-09-22T10:34:17.228026799-04:00
+hash: 876bc65024f66612325ebafcedeb3e4d5014d46b339cf7583f1c00c6bac6e32c
+updated: 2017-10-18T11:59:44.724549502+02:00
 imports:
 - name: github.com/btcsuite/btcd
   version: b8df516b4b267acf2de46be593a9d948d1d2c420
@@ -57,17 +57,15 @@ imports:
   - edwards25519
   - extra25519
 - name: github.com/tendermint/go-crypto
-  version: e6ea9499ff958479e4a921850d2382eb599f204c
+  version: 8e7f0e7701f92206679ad093d013b9b162427631
 - name: github.com/tendermint/go-wire
-  version: 5f88da3dbc1a72844e6dfaf274ce87f851d488eb
+  version: 26ee079df7fca1958da8995c727b59759b197534
   subpackages:
   - data
-- name: github.com/tendermint/merkleeyes
-  version: 2f6e5d31e7a35045d8d0a5895cb1fec33dd4d32b
-  subpackages:
-  - iavl
+- name: github.com/tendermint/iavl
+  version: ff4ffa531df48509d51f0c16c2432f986eed9fcc
 - name: github.com/tendermint/tmlibs
-  version: bffe6744ec277d60f707ab442e25513617842f8e
+  version: 8e5266a9ef2527e68a1571f932db8228a331b556
   subpackages:
   - common
   - db
diff --git a/glide.yaml b/glide.yaml
index 11379aad4..e8cf8302c 100644
--- a/glide.yaml
+++ b/glide.yaml
@@ -8,10 +8,8 @@ import:
   version: develop
 - package: github.com/tendermint/go-wire
   version: develop
-- package: github.com/tendermint/merkleeyes
+- package: github.com/tendermint/iavl
   version: develop
-  subpackages:
-  - iavl
 - package: github.com/tendermint/tmlibs
   version: develop
   subpackages: