diff --git a/app/store.go b/app/store.go
index 7163c02e26..87373d7051 100644
--- a/app/store.go
+++ b/app/store.go
@@ -46,8 +46,8 @@ func MockStore() *Store {
 	return res
 }
 
-// NewStore initializes an in-memory IAVLTree, or attempts to load a persistant
-// tree from disk
+// NewStore initializes an in-memory iavl.VersionedTree, or attempts to load a
+// persistant tree from disk
 func NewStore(dbName string, cacheSize int, logger log.Logger) (*Store, error) {
 	// start at 1 so the height returned by query is for the
 	// next block, ie. the one that includes the AppHash for our current state
@@ -55,9 +55,9 @@ func NewStore(dbName string, cacheSize int, logger log.Logger) (*Store, error) {
 
 	// Non-persistent case
 	if dbName == "" {
-		tree := iavl.NewIAVLTree(
+		tree := iavl.NewVersionedTree(
 			0,
-			nil,
+			dbm.NewMemDB(),
 		)
 		store := &Store{
 			State:  state.NewState(tree, false),
@@ -85,24 +85,26 @@ func NewStore(dbName string, cacheSize int, logger log.Logger) (*Store, error) {
 
 	// Open database called "dir/name.db", if it doesn't exist it will be created
 	db := dbm.NewDB(name, dbm.LevelDBBackendStr, dir)
-	tree := iavl.NewIAVLTree(cacheSize, db)
+	tree := iavl.NewVersionedTree(cacheSize, db)
 
 	var chainState ChainState
 	if empty {
 		logger.Info("no existing db, creating new db")
 		chainState = ChainState{
-			Hash:   tree.Save(),
+			Hash:   nil,
 			Height: initialHeight,
 		}
 		db.Set(stateKey, wire.BinaryBytes(chainState))
 	} else {
 		logger.Info("loading existing db")
 		eyesStateBytes := db.Get(stateKey)
-		err = wire.ReadBinaryBytes(eyesStateBytes, &chainState)
-		if err != nil {
+
+		if err = wire.ReadBinaryBytes(eyesStateBytes, &chainState); err != nil {
 			return nil, errors.Wrap(err, "Reading MerkleEyesState")
 		}
-		tree.Load(chainState.Hash)
+		if err = tree.Load(); err != nil {
+			return nil, errors.Wrap(err, "Loading tree")
+		}
 	}
 
 	res := &Store{
diff --git a/stack/checkpoint_test.go b/stack/checkpoint_test.go
index c5c582f90f..1cad0121e4 100644
--- a/stack/checkpoint_test.go
+++ b/stack/checkpoint_test.go
@@ -8,6 +8,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/tendermint/iavl"
+	db "github.com/tendermint/tmlibs/db"
 	"github.com/tendermint/tmlibs/log"
 
 	sdk "github.com/cosmos/cosmos-sdk"
@@ -17,7 +18,7 @@ import (
 func makeState() state.SimpleDB {
 	// return state.NewMemKVStore()
 
-	return state.NewBonsai(iavl.NewIAVLTree(0, nil))
+	return state.NewBonsai(iavl.NewVersionedTree(0, db.NewMemDB()))
 
 	// tree with persistence....
 	// tmpDir, err := ioutil.TempDir("", "state-tests")
diff --git a/state/bonsai.go b/state/bonsai.go
index 7224118410..973cd672da 100644
--- a/state/bonsai.go
+++ b/state/bonsai.go
@@ -12,7 +12,7 @@ type nonce int64
 // Bonsai is a deformed tree forced to fit in a small pot
 type Bonsai struct {
 	id   nonce
-	Tree *iavl.IAVLTree
+	Tree *iavl.VersionedTree
 }
 
 func (b *Bonsai) String() string {
@@ -22,7 +22,7 @@ func (b *Bonsai) String() string {
 var _ SimpleDB = &Bonsai{}
 
 // NewBonsai wraps a merkle tree and tags it to track children
-func NewBonsai(tree *iavl.IAVLTree) *Bonsai {
+func NewBonsai(tree *iavl.VersionedTree) *Bonsai {
 	return &Bonsai{
 		id:   nonce(rand.Int63()),
 		Tree: tree,
diff --git a/state/merkle.go b/state/merkle.go
index 06bfedb07b..d232a050d1 100644
--- a/state/merkle.go
+++ b/state/merkle.go
@@ -11,7 +11,7 @@ type State struct {
 	persistent bool
 }
 
-func NewState(tree *iavl.IAVLTree, persistent bool) State {
+func NewState(tree *iavl.VersionedTree, persistent bool) State {
 	base := NewBonsai(tree)
 	return State{
 		committed:  base,
@@ -70,7 +70,11 @@ func (s *State) Commit() ([]byte, error) {
 
 	var hash []byte
 	if s.persistent {
-		hash = s.committed.Tree.Save()
+		nextVersion := s.committed.Tree.LatestVersion() + 1
+		hash, err = s.committed.Tree.SaveVersion(nextVersion)
+		if err != nil {
+			return nil, err
+		}
 	} else {
 		hash = s.committed.Tree.Hash()
 	}
diff --git a/state/merkle_test.go b/state/merkle_test.go
index 03575c835b..fa039956de 100644
--- a/state/merkle_test.go
+++ b/state/merkle_test.go
@@ -7,6 +7,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/tendermint/iavl"
+	db "github.com/tendermint/tmlibs/db"
 )
 
 type keyVal struct {
@@ -64,7 +65,7 @@ func TestStateCommitHash(t *testing.T) {
 			result := make([][]byte, len(tc.rounds))
 
 			// make the store...
-			tree := iavl.NewIAVLTree(0, nil)
+			tree := iavl.NewVersionedTree(0, db.NewMemDB())
 			store := NewState(tree, false)
 
 			for n, r := range tc.rounds {
diff --git a/state/store_test.go b/state/store_test.go
index 47f7ccd2c0..ea72291702 100644
--- a/state/store_test.go
+++ b/state/store_test.go
@@ -17,11 +17,11 @@ func GetDBs() []SimpleDB {
 		panic(err)
 	}
 	db := dbm.NewDB("test-get-dbs", dbm.LevelDBBackendStr, tmpDir)
-	persist := iavl.NewIAVLTree(500, db)
+	persist := iavl.NewVersionedTree(500, db)
 
 	return []SimpleDB{
 		NewMemKVStore(),
-		NewBonsai(iavl.NewIAVLTree(0, nil)),
+		NewBonsai(iavl.NewVersionedTree(0, dbm.NewMemDB())),
 		NewBonsai(persist),
 	}
 }