diff --git a/core/blockchain.go b/core/blockchain.go
index 95ed06d8d6..0878597b36 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -1195,11 +1195,9 @@ func (self *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 			return i, err
 		}
 		// Write state changes to database
-		_, err = statedb.Commit()
-		if err != nil {
+		if _, err = statedb.CommitIndexed([]common.Hash{block.Hash()}); err != nil {
 			return i, err
 		}
-
 		// coalesce logs for later processing
 		coalescedLogs = append(coalescedLogs, logs...)
 
diff --git a/core/blockchain_test.go b/core/blockchain_test.go
index b4ac1696a3..7afc829efd 100644
--- a/core/blockchain_test.go
+++ b/core/blockchain_test.go
@@ -153,7 +153,7 @@ func testBlockChainImport(chain types.Blocks, blockchain *BlockChain) error {
 		blockchain.mu.Lock()
 		WriteTd(blockchain.chainDb, block.Hash(), new(big.Int).Add(block.Difficulty(), blockchain.GetTd(block.ParentHash())))
 		WriteBlock(blockchain.chainDb, block)
-		statedb.Commit()
+		statedb.CommitIndexed([]common.Hash{block.Hash()})
 		blockchain.mu.Unlock()
 	}
 	return nil
diff --git a/core/chain_makers.go b/core/chain_makers.go
index c62618e6cb..761d61901d 100644
--- a/core/chain_makers.go
+++ b/core/chain_makers.go
@@ -171,12 +171,14 @@ func GenerateChain(parent *types.Block, db ethdb.Database, n int, gen func(int,
 			gen(i, b)
 		}
 		AccumulateRewards(statedb, h, b.uncles)
-		root, err := statedb.Commit()
-		if err != nil {
+
+		h.Root = statedb.IntermediateRoot()
+		block := types.NewBlock(h, b.txs, b.uncles, b.receipts)
+
+		if _, err := statedb.CommitIndexed([]common.Hash{block.Hash()}); err != nil {
 			panic(fmt.Sprintf("state write error: %v", err))
 		}
-		h.Root = root
-		return types.NewBlock(h, b.txs, b.uncles, b.receipts), b.receipts
+		return block, b.receipts
 	}
 	for i := 0; i < n; i++ {
 		statedb, err := state.New(parent.Root(), db)
diff --git a/core/genesis.go b/core/genesis.go
index d8c6e9cea3..ed4949194c 100644
--- a/core/genesis.go
+++ b/core/genesis.go
@@ -72,8 +72,6 @@ func WriteGenesisBlock(chainDb ethdb.Database, reader io.Reader) (*types.Block,
 			statedb.SetState(address, common.HexToHash(key), common.HexToHash(value))
 		}
 	}
-	root, stateBatch := statedb.CommitBatch()
-
 	difficulty := common.String2Big(genesis.Difficulty)
 	block := types.NewBlock(&types.Header{
 		Nonce:      types.EncodeNonce(common.String2Big(genesis.Nonce).Uint64()),
@@ -84,7 +82,7 @@ func WriteGenesisBlock(chainDb ethdb.Database, reader io.Reader) (*types.Block,
 		Difficulty: difficulty,
 		MixDigest:  common.HexToHash(genesis.Mixhash),
 		Coinbase:   common.HexToAddress(genesis.Coinbase),
-		Root:       root,
+		Root:       statedb.IntermediateRoot(),
 	}, nil, nil, nil)
 
 	if block := GetBlock(chainDb, block.Hash()); block != nil {
@@ -95,8 +93,7 @@ func WriteGenesisBlock(chainDb ethdb.Database, reader io.Reader) (*types.Block,
 		}
 		return block, nil
 	}
-
-	if err := stateBatch.Write(); err != nil {
+	if _, err := statedb.CommitIndexed([]common.Hash{block.Hash()}); err != nil {
 		return nil, fmt.Errorf("cannot write state: %v", err)
 	}
 	if err := WriteTd(chainDb, block.Hash(), difficulty); err != nil {
@@ -123,15 +120,16 @@ func GenesisBlockForTesting(db ethdb.Database, addr common.Address, balance *big
 	statedb, _ := state.New(common.Hash{}, db)
 	obj := statedb.GetOrNewStateObject(addr)
 	obj.SetBalance(balance)
-	root, err := statedb.Commit()
-	if err != nil {
-		panic(fmt.Sprintf("cannot write state: %v", err))
-	}
+
 	block := types.NewBlock(&types.Header{
 		Difficulty: params.GenesisDifficulty,
 		GasLimit:   params.GenesisGasLimit,
-		Root:       root,
+		Root:       statedb.IntermediateRoot(),
 	}, nil, nil, nil)
+
+	if _, err := statedb.CommitIndexed([]common.Hash{block.Hash()}); err != nil {
+		panic(fmt.Sprintf("cannot write state: %v", err))
+	}
 	return block
 }
 
diff --git a/core/index_test.go b/core/index_test.go
new file mode 100644
index 0000000000..2d4a8635b3
--- /dev/null
+++ b/core/index_test.go
@@ -0,0 +1,155 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package core
+
+import (
+	"bytes"
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/state"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/trie"
+)
+
+// blackHoleContract is a trivial Ethereum contract that can just store some data
+// points in its state trie. It's goal is to have a means to test functionality
+// depending on evolving state roots.
+//
+// contract BlackHole {
+//     mapping (int256 => uint) public data;
+//
+//     function set(int256 key, uint value) {
+//         data[key] = value;
+//     }
+// }
+var blackHoleContract = common.Hex2Bytes("6060604052605f8060106000396000f3606060405260e060020a60003504639398e0cd81146024578063a22c554014603b575b005b605560043560006020819052908152604090205481565b600435600090815260208190526040902060243590556022565b6060908152602090f3")
+var blackHoleSetter = common.Hex2Bytes("a22c5540")
+
+// Tests that state trie indexes are properly constructed for an entire chain of
+// imported blocks, cross referencing between various state roots, as well as
+// making sure that state updates do not lose reference entries.
+func TestChainIndex(t *testing.T) {
+	// Configure the test chain and ensure we have enough funds to play with
+	var (
+		key1, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
+		key2, _ = crypto.HexToECDSA("8a1f9a8f95be41cd7ccb6168179afb4504aefe388d1e14474d32c45c72ce7b7a")
+		key3, _ = crypto.HexToECDSA("49a7b37aa6f6645917e7b807e9d1c00d4fa71f18343b0d4122a4d2df64dd6fee")
+		addr1   = crypto.PubkeyToAddress(key1.PublicKey)
+		addr2   = crypto.PubkeyToAddress(key2.PublicKey)
+		addr3   = crypto.PubkeyToAddress(key3.PublicKey)
+		db, _   = ethdb.NewMemDatabase()
+	)
+	genesis := WriteGenesisBlockForTesting(db, GenesisAccount{addr1, big.NewInt(10000000000)})
+
+	// Generate a chain will all kinds of events happening in it
+	var contract common.Address
+
+	chain, _ := GenerateChain(genesis, db, 8, func(i int, gen *BlockGen) {
+		switch i {
+		case 0:
+			// In block 1, addr1 sends addr2 some ether.
+			tx, _ := types.NewTransaction(gen.TxNonce(addr1), addr2, big.NewInt(10000), params.TxGas, nil, nil).SignECDSA(key1)
+			gen.AddTx(tx)
+		case 1:
+			// In block 2, addr1 sends some more ether to addr2.
+			// addr2 passes it on to addr3.
+			tx1, _ := types.NewTransaction(gen.TxNonce(addr1), addr2, big.NewInt(1000), params.TxGas, nil, nil).SignECDSA(key1)
+			tx2, _ := types.NewTransaction(gen.TxNonce(addr2), addr3, big.NewInt(1000), params.TxGas, nil, nil).SignECDSA(key2)
+			gen.AddTx(tx1)
+			gen.AddTx(tx2)
+		case 2:
+			// Block 3 is empty but was mined by addr3.
+			gen.SetCoinbase(addr3)
+			gen.SetExtra([]byte("yeehaw"))
+		case 3:
+			// Block 4 includes blocks 2 and 3 as uncle headers (with modified extra data).
+			b2 := gen.PrevBlock(1).Header()
+			b2.Extra = []byte("foo")
+			gen.AddUncle(b2)
+			b3 := gen.PrevBlock(2).Header()
+			b3.Extra = []byte("foo")
+			gen.AddUncle(b3)
+		case 4:
+			// In block 5, we create a simple storage contract to add data entries to
+			tx, _ := types.NewContractCreation(gen.TxNonce(addr1), big.NewInt(31415), params.GenesisGasLimit, big.NewInt(1), blackHoleContract).SignECDSA(key1)
+			contract = crypto.CreateAddress(addr1, tx.Nonce())
+			gen.AddTx(tx)
+		case 5:
+			// In block 6, we store a single entry into the storage to check single update indexing
+			key := common.Hex2BytesFixed("01", 32)
+			val := common.Hex2BytesFixed("02", 32)
+
+			tx, _ := types.NewTransaction(gen.TxNonce(addr1), contract, nil, params.GenesisGasLimit, nil, append(append(blackHoleSetter, key...), val...)).SignECDSA(key1)
+			gen.AddTx(tx)
+		case 6:
+			// In block 7, we store a lot of entries into the storage to check multi update indexing
+			for i := int64(0); i < 50; i++ {
+				key := common.Hex2BytesFixed(common.Bytes2Hex(big.NewInt(i).Bytes()), 32)
+				val := common.Hex2BytesFixed(common.Bytes2Hex(big.NewInt(i+2).Bytes()), 32)
+
+				tx, _ := types.NewTransaction(gen.TxNonce(addr1), contract, nil, big.NewInt(45000), nil, append(append(blackHoleSetter, key...), val...)).SignECDSA(key1)
+				gen.AddTx(tx)
+			}
+		}
+	})
+	// Import the chain. This runs all block validation rules.
+	evmux := &event.TypeMux{}
+
+	blockchain, _ := NewBlockChain(db, FakePow{}, evmux)
+	if i, err := blockchain.InsertChain(chain); err != nil {
+		t.Fatalf("block %d: insert failed: %v\n", i, err)
+		return
+	}
+	// Iterate over all the blocks and check the state trie indexes
+	indexes := make(map[string]struct{})
+
+	for num := uint64(0); num <= blockchain.CurrentBlock().NumberU64(); num++ {
+		// Gather all the indexes that should be present in the state trie
+		block := blockchain.GetBlockByNumber(num)
+
+		stateDb, err := state.New(block.Root(), db)
+		if err != nil {
+			t.Fatalf("failed to create state trie at %x: %v", block.Root(), err)
+		}
+		for it := state.NewNodeIterator(stateDb); it.Next(); {
+			if (it.Hash != common.Hash{}) && (it.Parent != common.Hash{}) {
+				indexes[string(trie.ParentReferenceIndexKey(it.Parent.Bytes(), it.Hash.Bytes()))] = struct{}{}
+			}
+		}
+		// Add the block->state index entries
+		indexes[string(trie.ParentReferenceIndexKey(block.Hash().Bytes(), block.Root().Bytes()))] = struct{}{}
+	}
+	// Cross check the indexes and the database itself
+	for index, _ := range indexes {
+		if _, err := db.Get([]byte(index)); err != nil {
+			t.Errorf("failed to retrieve reported index %x: %v", index, err)
+		}
+	}
+	for _, key := range db.Keys() {
+		if bytes.HasPrefix(key, trie.ParentReferenceIndexPrefix) {
+			if _, ok := indexes[string(key)]; !ok {
+				t.Errorf("index entry not reported %x", key)
+			}
+		}
+	}
+}
diff --git a/core/state/index_test.go b/core/state/index_test.go
index 25f1f853f2..8b349857eb 100644
--- a/core/state/index_test.go
+++ b/core/state/index_test.go
@@ -26,9 +26,16 @@ import (
 )
 
 // Tests that all index entries are stored in the database after a state commit.
-func TestStateIndex(t *testing.T) {
+func TestStateIndexDangling(t *testing.T) {
+	testStateIndex(t, nil)
+}
+func TestStateIndexRooted(t *testing.T) {
+	testStateIndex(t, []common.Hash{common.BytesToHash([]byte{0x01}), common.BytesToHash([]byte{0x02, 0x03})})
+}
+
+func testStateIndex(t *testing.T, referrers []common.Hash) {
 	// Create some arbitrary test state to iterate
-	db, root, _ := makeTestState()
+	db, root, _ := makeTestState(referrers)
 
 	state, err := New(root, db)
 	if err != nil {
@@ -41,6 +48,9 @@ func TestStateIndex(t *testing.T) {
 			indexes[string(trie.ParentReferenceIndexKey(it.Parent.Bytes(), it.Hash.Bytes()))] = struct{}{}
 		}
 	}
+	for _, referrer := range referrers {
+		indexes[string(trie.ParentReferenceIndexKey(referrer.Bytes(), root.Bytes()))] = struct{}{}
+	}
 	// Cross check the indexes and the database itself
 	for index, _ := range indexes {
 		if _, err := db.Get([]byte(index)); err != nil {
diff --git a/core/state/iterator_test.go b/core/state/iterator_test.go
index df0135296a..d44e15be7d 100644
--- a/core/state/iterator_test.go
+++ b/core/state/iterator_test.go
@@ -28,7 +28,7 @@ import (
 // Tests that the node iterator indeed walks over the entire database contents.
 func TestNodeIteratorCoverage(t *testing.T) {
 	// Create some arbitrary test state to iterate
-	db, root, _ := makeTestState()
+	db, root, _ := makeTestState(nil)
 
 	state, err := New(root, db)
 	if err != nil {
diff --git a/core/state/state_object.go b/core/state/state_object.go
index 47546112f4..292f32f301 100644
--- a/core/state/state_object.go
+++ b/core/state/state_object.go
@@ -118,7 +118,7 @@ func (c *StateObject) setAddr(addr []byte, value common.Hash) {
 		// if RLPing failed we better panic and not fail silently. This would be considered a consensus issue
 		panic(err)
 	}
-	c.trie.Update(addr, v)
+	c.trie.UpdateIndexed(addr, v, nil)
 }
 
 func (self *StateObject) Storage() Storage {
diff --git a/core/state/state_test.go b/core/state/state_test.go
index 7ce341c361..040683ae9d 100644
--- a/core/state/state_test.go
+++ b/core/state/state_test.go
@@ -89,7 +89,7 @@ func TestNull(t *testing.T) {
 	//value := common.FromHex("0x823140710bf13990e4500136726d8b55")
 	var value common.Hash
 	state.SetState(address, common.Hash{}, value)
-	state.Commit()
+	state.CommitIndexed(nil)
 	value = state.GetState(address, common.Hash{})
 	if !common.EmptyHash(value) {
 		t.Errorf("expected empty hash. got %x", value)
diff --git a/core/state/statedb.go b/core/state/statedb.go
index e8e1e269e2..1077e3ccd8 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -353,22 +353,22 @@ func (s *StateDB) IntermediateRoot() common.Hash {
 	return s.trie.Hash()
 }
 
-// Commit commits all state changes to the database.
-func (s *StateDB) Commit() (root common.Hash, err error) {
-	root, batch := s.CommitBatch()
+// CommitIndexed commits all state changes to the database.
+func (s *StateDB) CommitIndexed(refs []common.Hash) (root common.Hash, err error) {
+	root, batch := s.CommitBatchIndexed(refs)
 	return root, batch.Write()
 }
 
-// CommitBatch commits all state changes to a write batch but does not
+// CommitBatchIndexed commits all state changes to a write batch but does not
 // execute the batch. It is used to validate state changes against
 // the root hash stored in a block.
-func (s *StateDB) CommitBatch() (root common.Hash, batch ethdb.Batch) {
+func (s *StateDB) CommitBatchIndexed(refs []common.Hash) (root common.Hash, batch ethdb.Batch) {
 	batch = s.db.NewBatch()
-	root, _ = s.commit(batch)
+	root, _ = s.commit(batch, refs)
 	return root, batch
 }
 
-func (s *StateDB) commit(db trie.DatabaseWriter) (common.Hash, error) {
+func (s *StateDB) commit(db trie.DatabaseWriter, refs []common.Hash) (common.Hash, error) {
 	s.refund = new(big.Int)
 
 	for _, stateObject := range s.stateObjects {
@@ -383,7 +383,7 @@ func (s *StateDB) commit(db trie.DatabaseWriter) (common.Hash, error) {
 			// This updates the trie root internally, so
 			// getting the root hash of the storage trie
 			// through UpdateStateObject is fast.
-			if _, err := stateObject.trie.CommitTo(db); err != nil {
+			if _, err := stateObject.trie.CommitToIndexed(db, nil); err != nil {
 				return common.Hash{}, err
 			}
 			// Update the object in the account trie.
@@ -391,7 +391,11 @@ func (s *StateDB) commit(db trie.DatabaseWriter) (common.Hash, error) {
 		}
 		stateObject.dirty = false
 	}
-	return s.trie.CommitTo(db)
+	referrers := make([][]byte, len(refs))
+	for i, ref := range refs {
+		referrers[i] = ref.Bytes()
+	}
+	return s.trie.CommitToIndexed(db, referrers)
 }
 
 func (self *StateDB) Refunds() *big.Int {
diff --git a/core/state/sync.go b/core/state/sync.go
index ef2b4b84c5..5d77517e7e 100644
--- a/core/state/sync.go
+++ b/core/state/sync.go
@@ -32,7 +32,7 @@ import (
 type StateSync trie.TrieSync
 
 // NewStateSync create a new state trie download scheduler.
-func NewStateSync(root common.Hash, database ethdb.Database) *StateSync {
+func NewStateSync(root common.Hash, database ethdb.Database, parent common.Hash) *StateSync {
 	var syncer *trie.TrieSync
 
 	callback := func(leaf []byte, parent common.Hash) error {
@@ -50,7 +50,7 @@ func NewStateSync(root common.Hash, database ethdb.Database) *StateSync {
 
 		return nil
 	}
-	syncer = trie.NewTrieSync(root, database, callback)
+	syncer = trie.NewTrieSync(root, database, parent, callback)
 	return (*StateSync)(syncer)
 }
 
diff --git a/core/state/sync_test.go b/core/state/sync_test.go
index 5e59c8f9cd..30cd70eec6 100644
--- a/core/state/sync_test.go
+++ b/core/state/sync_test.go
@@ -37,7 +37,7 @@ type testAccount struct {
 }
 
 // makeTestState create a sample test state to test node-wise reconstruction.
-func makeTestState() (ethdb.Database, common.Hash, []*testAccount) {
+func makeTestState(referrers []common.Hash) (ethdb.Database, common.Hash, []*testAccount) {
 	// Create an empty state
 	db, _ := ethdb.NewMemDatabase()
 	state, _ := New(common.Hash{}, db)
@@ -61,7 +61,7 @@ func makeTestState() (ethdb.Database, common.Hash, []*testAccount) {
 		state.UpdateStateObject(obj)
 		accounts = append(accounts, acc)
 	}
-	root, _ := state.Commit()
+	root, _ := state.CommitIndexed(referrers)
 
 	// Remove any potentially cached data from the test state creation
 	trie.ClearGlobalCache()
@@ -72,7 +72,7 @@ func makeTestState() (ethdb.Database, common.Hash, []*testAccount) {
 
 // checkStateAccounts cross references a reconstructed state with an expected
 // account array.
-func checkStateAccounts(t *testing.T, db ethdb.Database, root common.Hash, accounts []*testAccount) {
+func checkStateAccounts(t *testing.T, db ethdb.Database, root common.Hash, accounts []*testAccount, parent common.Hash) {
 	// Remove any potentially cached data from the state synchronisation
 	trie.ClearGlobalCache()
 
@@ -84,7 +84,7 @@ func checkStateAccounts(t *testing.T, db ethdb.Database, root common.Hash, accou
 	if err := checkStateConsistency(db, root); err != nil {
 		t.Fatalf("inconsistent state trie at %x: %v", root, err)
 	}
-	if err := checkStateIndex(db, root); err != nil {
+	if err := checkStateIndex(db, root, parent); err != nil {
 		t.Fatalf("index error at %x: %v", root, err)
 	}
 	for i, acc := range accounts {
@@ -126,23 +126,37 @@ func checkStateConsistency(db ethdb.Database, root common.Hash) (failure error)
 
 // checkStateIndex iterates over the entire state trie and checks that all required
 // database indexes have been generated by the synchronizer.
-func checkStateIndex(db ethdb.Database, root common.Hash) error {
+func checkStateIndex(db ethdb.Database, root common.Hash, parent common.Hash) error {
 	// Remove any potentially cached data from the test state creation or previous checks
 	trie.ClearGlobalCache()
 
-	// Create and iterate a state trie rooted in a sub-node
 	if _, err := db.Get(root.Bytes()); err != nil {
 		return err
 	}
 	state, err := New(root, db)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to create state trie at %x: %v", root, err)
 	}
+	// Gather all the indexes that should be present in the database
+	indexes := make(map[string]struct{})
 	for it := NewNodeIterator(state); it.Next(); {
 		if (it.Hash != common.Hash{}) && (it.Parent != common.Hash{}) {
-			parentRef := trie.ParentReferenceIndexKey(it.Parent.Bytes(), it.Hash.Bytes())
-			if _, err := db.Get(parentRef); err != nil {
-				return fmt.Errorf("parent reference lookup %x: %v", parentRef, err)
+			indexes[string(trie.ParentReferenceIndexKey(it.Parent.Bytes(), it.Hash.Bytes()))] = struct{}{}
+		}
+	}
+	if parent != (common.Hash{}) {
+		indexes[string(trie.ParentReferenceIndexKey(parent.Bytes(), root.Bytes()))] = struct{}{}
+	}
+	// Cross check the indexes and the database itself
+	for index, _ := range indexes {
+		if _, err := db.Get([]byte(index)); err != nil {
+			return fmt.Errorf("failed to retrieve reported index %x: %v", index, err)
+		}
+	}
+	for _, key := range db.(*ethdb.MemDatabase).Keys() {
+		if bytes.HasPrefix(key, trie.ParentReferenceIndexPrefix) {
+			if _, ok := indexes[string(key)]; !ok {
+				return fmt.Errorf("index entry not reported %x", key)
 			}
 		}
 	}
@@ -150,26 +164,39 @@ func checkStateIndex(db ethdb.Database, root common.Hash) error {
 }
 
 // Tests that an empty state is not scheduled for syncing.
-func TestEmptyStateSync(t *testing.T) {
+func TestEmptyStateSyncDangling(t *testing.T) { testEmptyStateSync(t, common.Hash{}) }
+func TestEmptyStateSyncRooted(t *testing.T)   { testEmptyStateSync(t, common.BytesToHash([]byte{0x01})) }
+
+func testEmptyStateSync(t *testing.T, origin common.Hash) {
 	empty := common.HexToHash("56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421")
 	db, _ := ethdb.NewMemDatabase()
-	if req := NewStateSync(empty, db).Missing(1); len(req) != 0 {
+	if req := NewStateSync(empty, db, origin).Missing(1); len(req) != 0 {
 		t.Errorf("content requested for empty state: %v", req)
 	}
 }
 
 // Tests that given a root hash, a state can sync iteratively on a single thread,
 // requesting retrieval tasks and returning all of them in one go.
-func TestIterativeStateSyncIndividual(t *testing.T) { testIterativeStateSync(t, 1) }
-func TestIterativeStateSyncBatched(t *testing.T)    { testIterativeStateSync(t, 100) }
+func TestIterativeStateSyncIndividualDangling(t *testing.T) {
+	testIterativeStateSync(t, 1, common.Hash{})
+}
+func TestIterativeStateSyncIndividualRooted(t *testing.T) {
+	testIterativeStateSync(t, 1, common.BytesToHash([]byte{0x02}))
+}
+func TestIterativeStateSyncBatchedDangling(t *testing.T) {
+	testIterativeStateSync(t, 100, common.Hash{})
+}
+func TestIterativeStateSyncBatchedRooted(t *testing.T) {
+	testIterativeStateSync(t, 100, common.BytesToHash([]byte{0x03}))
+}
 
-func testIterativeStateSync(t *testing.T, batch int) {
+func testIterativeStateSync(t *testing.T, batch int, origin common.Hash) {
 	// Create a random state to copy
-	srcDb, srcRoot, srcAccounts := makeTestState()
+	srcDb, srcRoot, srcAccounts := makeTestState(nil)
 
 	// Create a destination state and sync with the scheduler
 	dstDb, _ := ethdb.NewMemDatabase()
-	sched := NewStateSync(srcRoot, dstDb)
+	sched := NewStateSync(srcRoot, dstDb, origin)
 
 	queue := append([]common.Hash{}, sched.Missing(batch)...)
 	for len(queue) > 0 {
@@ -187,18 +214,25 @@ func testIterativeStateSync(t *testing.T, batch int) {
 		queue = append(queue[:0], sched.Missing(batch)...)
 	}
 	// Cross check that the two states are in sync
-	checkStateAccounts(t, dstDb, srcRoot, srcAccounts)
+	checkStateAccounts(t, dstDb, srcRoot, srcAccounts, origin)
 }
 
 // Tests that the trie scheduler can correctly reconstruct the state even if only
 // partial results are returned, and the others sent only later.
-func TestIterativeDelayedStateSync(t *testing.T) {
+func TestIterativeDelayedStateSyncDangling(t *testing.T) {
+	testIterativeDelayedStateSync(t, common.Hash{})
+}
+func TestIterativeDelayedStateSyncRooted(t *testing.T) {
+	testIterativeDelayedStateSync(t, common.BytesToHash([]byte{0x04}))
+}
+
+func testIterativeDelayedStateSync(t *testing.T, origin common.Hash) {
 	// Create a random state to copy
-	srcDb, srcRoot, srcAccounts := makeTestState()
+	srcDb, srcRoot, srcAccounts := makeTestState(nil)
 
 	// Create a destination state and sync with the scheduler
 	dstDb, _ := ethdb.NewMemDatabase()
-	sched := NewStateSync(srcRoot, dstDb)
+	sched := NewStateSync(srcRoot, dstDb, origin)
 
 	queue := append([]common.Hash{}, sched.Missing(0)...)
 	for len(queue) > 0 {
@@ -217,22 +251,32 @@ func TestIterativeDelayedStateSync(t *testing.T) {
 		queue = append(queue[len(results):], sched.Missing(0)...)
 	}
 	// Cross check that the two states are in sync
-	checkStateAccounts(t, dstDb, srcRoot, srcAccounts)
+	checkStateAccounts(t, dstDb, srcRoot, srcAccounts, origin)
 }
 
 // Tests that given a root hash, a trie can sync iteratively on a single thread,
 // requesting retrieval tasks and returning all of them in one go, however in a
 // random order.
-func TestIterativeRandomStateSyncIndividual(t *testing.T) { testIterativeRandomStateSync(t, 1) }
-func TestIterativeRandomStateSyncBatched(t *testing.T)    { testIterativeRandomStateSync(t, 100) }
+func TestIterativeRandomStateSyncIndividualDangling(t *testing.T) {
+	testIterativeRandomStateSync(t, 1, common.Hash{})
+}
+func TestIterativeRandomStateSyncIndividualRooted(t *testing.T) {
+	testIterativeRandomStateSync(t, 1, common.BytesToHash([]byte{0x05}))
+}
+func TestIterativeRandomStateSyncBatchedDangling(t *testing.T) {
+	testIterativeRandomStateSync(t, 100, common.Hash{})
+}
+func TestIterativeRandomStateSyncBatchedRooted(t *testing.T) {
+	testIterativeRandomStateSync(t, 100, common.BytesToHash([]byte{0x06}))
+}
 
-func testIterativeRandomStateSync(t *testing.T, batch int) {
+func testIterativeRandomStateSync(t *testing.T, batch int, origin common.Hash) {
 	// Create a random state to copy
-	srcDb, srcRoot, srcAccounts := makeTestState()
+	srcDb, srcRoot, srcAccounts := makeTestState(nil)
 
 	// Create a destination state and sync with the scheduler
 	dstDb, _ := ethdb.NewMemDatabase()
-	sched := NewStateSync(srcRoot, dstDb)
+	sched := NewStateSync(srcRoot, dstDb, origin)
 
 	queue := make(map[common.Hash]struct{})
 	for _, hash := range sched.Missing(batch) {
@@ -258,18 +302,25 @@ func testIterativeRandomStateSync(t *testing.T, batch int) {
 		}
 	}
 	// Cross check that the two states are in sync
-	checkStateAccounts(t, dstDb, srcRoot, srcAccounts)
+	checkStateAccounts(t, dstDb, srcRoot, srcAccounts, origin)
 }
 
 // Tests that the trie scheduler can correctly reconstruct the state even if only
 // partial results are returned (Even those randomly), others sent only later.
-func TestIterativeRandomDelayedStateSync(t *testing.T) {
+func TestIterativeRandomDelayedStateSyncDangling(t *testing.T) {
+	testIterativeRandomDelayedStateSync(t, common.Hash{})
+}
+func TestIterativeRandomDelayedStateSyncRooted(t *testing.T) {
+	testIterativeRandomDelayedStateSync(t, common.BytesToHash([]byte{0x07}))
+}
+
+func testIterativeRandomDelayedStateSync(t *testing.T, origin common.Hash) {
 	// Create a random state to copy
-	srcDb, srcRoot, srcAccounts := makeTestState()
+	srcDb, srcRoot, srcAccounts := makeTestState(nil)
 
 	// Create a destination state and sync with the scheduler
 	dstDb, _ := ethdb.NewMemDatabase()
-	sched := NewStateSync(srcRoot, dstDb)
+	sched := NewStateSync(srcRoot, dstDb, origin)
 
 	queue := make(map[common.Hash]struct{})
 	for _, hash := range sched.Missing(0) {
@@ -300,18 +351,18 @@ func TestIterativeRandomDelayedStateSync(t *testing.T) {
 		}
 	}
 	// Cross check that the two states are in sync
-	checkStateAccounts(t, dstDb, srcRoot, srcAccounts)
+	checkStateAccounts(t, dstDb, srcRoot, srcAccounts, origin)
 }
 
 // Tests that at any point in time during a sync, only complete sub-tries are in
 // the database.
 func TestIncompleteStateSync(t *testing.T) {
 	// Create a random state to copy
-	srcDb, srcRoot, srcAccounts := makeTestState()
+	srcDb, srcRoot, srcAccounts := makeTestState(nil)
 
 	// Create a destination state and sync with the scheduler
 	dstDb, _ := ethdb.NewMemDatabase()
-	sched := NewStateSync(srcRoot, dstDb)
+	sched := NewStateSync(srcRoot, dstDb, common.Hash{})
 
 	added := []common.Hash{}
 	queue := append([]common.Hash{}, sched.Missing(1)...)
diff --git a/core/types/derive_sha.go b/core/types/derive_sha.go
index 00c42c5bc6..68d803e448 100644
--- a/core/types/derive_sha.go
+++ b/core/types/derive_sha.go
@@ -35,7 +35,7 @@ func DeriveSha(list DerivableList) common.Hash {
 	for i := 0; i < list.Len(); i++ {
 		keybuf.Reset()
 		rlp.Encode(keybuf, uint(i))
-		trie.Update(keybuf.Bytes(), list.GetRlp(i))
+		trie.UpdateIndexed(keybuf.Bytes(), list.GetRlp(i), nil)
 	}
 	return trie.Hash()
 }
diff --git a/eth/downloader/queue.go b/eth/downloader/queue.go
index 1e55560dbf..1f37ab6c00 100644
--- a/eth/downloader/queue.go
+++ b/eth/downloader/queue.go
@@ -356,7 +356,7 @@ func (q *queue) Schedule(headers []*types.Header, from uint64) []*types.Header {
 		if q.mode == FastSync && header.Number.Uint64() == q.fastSyncPivot {
 			// Pivoting point of the fast sync, retrieve the state tries
 			q.stateSchedLock.Lock()
-			q.stateScheduler = state.NewStateSync(header.Root, q.stateDatabase)
+			q.stateScheduler = state.NewStateSync(header.Root, q.stateDatabase, header.Hash())
 			q.stateSchedLock.Unlock()
 		}
 		inserts = append(inserts, header)
diff --git a/light/state_test.go b/light/state_test.go
index 2c2e6daea1..418dee83b5 100644
--- a/light/state_test.go
+++ b/light/state_test.go
@@ -65,7 +65,7 @@ func makeTestState() (common.Hash, ethdb.Database) {
 		so.Update()
 		st.UpdateStateObject(so)
 	}
-	root, _ := st.Commit()
+	root, _ := st.CommitIndexed(nil)
 	return root, sdb
 }
 
diff --git a/light/trie.go b/light/trie.go
index e9c96ea48e..d99fe3ca4c 100644
--- a/light/trie.go
+++ b/light/trie.go
@@ -89,19 +89,20 @@ func (t *LightTrie) Get(ctx context.Context, key []byte) (res []byte, err error)
 	return
 }
 
-// Update associates key with value in the trie. Subsequent calls to
-// Get will return value. If value has length zero, any existing value
-// is deleted from the trie and calls to Get will return nil.
+// UpdateIndexed associates key with value in the trie. Subsequent calls to Get
+// will return value. If value has length zero, any existing value is deleted
+// from the trie and calls to Get will return nil. In addition, state trie index
+// entries are also generated for all entities referencing the current node.
 //
 // The value bytes must not be modified by the caller while they are
 // stored in the trie.
-func (t *LightTrie) Update(ctx context.Context, key, value []byte) (err error) {
+func (t *LightTrie) UpdateIndexed(ctx context.Context, key, value []byte, references [][]byte) (err error) {
 	err = t.do(ctx, key, func() (err error) {
 		if t.trie == nil {
 			t.trie, err = trie.NewSecure(t.originalRoot, t.db)
 		}
 		if err == nil {
-			err = t.trie.TryUpdate(key, value)
+			err = t.trie.TryUpdateIndexed(key, value, references)
 		}
 		return
 	})
diff --git a/miner/worker.go b/miner/worker.go
index 1a411ae20b..648cbb57fd 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -284,7 +284,7 @@ func (self *worker) wait() {
 				}
 				go self.mux.Post(core.NewMinedBlockEvent{block})
 			} else {
-				work.state.Commit()
+				work.state.CommitIndexed([]common.Hash{block.Hash()})
 				parent := self.chain.GetBlock(block.ParentHash())
 				if parent == nil {
 					glog.V(logger.Error).Infoln("Invalid block found during mining")
diff --git a/tests/block_test_util.go b/tests/block_test_util.go
index 473bc3419f..9503497380 100644
--- a/tests/block_test_util.go
+++ b/tests/block_test_util.go
@@ -250,7 +250,7 @@ func (t *BlockTest) InsertPreState(db ethdb.Database, am *accounts.Manager) (*st
 		}
 	}
 
-	root, err := statedb.Commit()
+	root, err := statedb.CommitIndexed(nil)
 	if err != nil {
 		return nil, fmt.Errorf("error writing state: %v", err)
 	}
diff --git a/tests/state_test_util.go b/tests/state_test_util.go
index 352fe3570b..1e71fa93a5 100644
--- a/tests/state_test_util.go
+++ b/tests/state_test_util.go
@@ -201,7 +201,7 @@ func runStateTest(test VmTest) error {
 		}
 	}
 
-	root, _ := statedb.Commit()
+	root, _ := statedb.CommitIndexed(nil)
 	if common.HexToHash(test.PostStateRoot) != root {
 		return fmt.Errorf("Post state root error. Expected %s, got %x", test.PostStateRoot, root)
 	}
@@ -245,7 +245,7 @@ func RunState(statedb *state.StateDB, env, tx map[string]string) ([]byte, vm.Log
 	if core.IsNonceErr(err) || core.IsInvalidTxErr(err) || core.IsGasLimitErr(err) {
 		statedb.Set(snapshot)
 	}
-	statedb.Commit()
+	statedb.CommitIndexed(nil)
 
 	return ret, vmenv.state.Logs(), vmenv.Gas, err
 }
diff --git a/trie/index_test.go b/trie/index_test.go
index 1ecf8dd7bf..9baa894d3c 100644
--- a/trie/index_test.go
+++ b/trie/index_test.go
@@ -25,9 +25,12 @@ import (
 )
 
 // Tests that all index entries are stored in the database after a trie commit.
-func TestTrieIndex(t *testing.T) {
+func TestTrieIndexDangling(t *testing.T) { testTrieIndex(t, nil) }
+func TestTrieIndexRooted(t *testing.T)   { testTrieIndex(t, [][]byte{[]byte{0x00}, []byte{0x00, 0x01}}) }
+
+func testTrieIndex(t *testing.T, referrers [][]byte) {
 	// Create some arbitrary test trie to iterate
-	db, trie, _ := makeTestTrie()
+	db, trie, _ := makeTestTrie(referrers)
 
 	// Gather all the indexes that should be present in the database
 	indexes := make(map[string]struct{})
@@ -36,6 +39,9 @@ func TestTrieIndex(t *testing.T) {
 			indexes[string(ParentReferenceIndexKey(it.Parent.Bytes(), it.Hash.Bytes()))] = struct{}{}
 		}
 	}
+	for _, referrer := range referrers {
+		indexes[string(ParentReferenceIndexKey(referrer, trie.Hash().Bytes()))] = struct{}{}
+	}
 	// Cross check the indexes and the database itself
 	for index, _ := range indexes {
 		if _, err := db.Get([]byte(index)); err != nil {
diff --git a/trie/iterator_test.go b/trie/iterator_test.go
index 815743bfdc..b095de855e 100644
--- a/trie/iterator_test.go
+++ b/trie/iterator_test.go
@@ -37,9 +37,9 @@ func TestIterator(t *testing.T) {
 	v := make(map[string]bool)
 	for _, val := range vals {
 		v[val.k] = false
-		trie.Update([]byte(val.k), []byte(val.v))
+		trie.UpdateIndexed([]byte(val.k), []byte(val.v), nil)
 	}
-	trie.Commit()
+	trie.CommitIndexed(nil)
 
 	it := NewIterator(trie)
 	for it.Next() {
@@ -56,7 +56,7 @@ func TestIterator(t *testing.T) {
 // Tests that the node iterator indeed walks over the entire database contents.
 func TestNodeIteratorCoverage(t *testing.T) {
 	// Create some arbitrary test trie to iterate
-	db, trie, _ := makeTestTrie()
+	db, trie, _ := makeTestTrie(nil)
 
 	// Gather all the node hashes found by the iterator
 	hashes := make(map[common.Hash]struct{})
diff --git a/trie/proof.go b/trie/proof.go
index 3c49309026..0cfdc5bc72 100644
--- a/trie/proof.go
+++ b/trie/proof.go
@@ -62,7 +62,7 @@ func (t *Trie) Prove(key []byte) []rlp.RawValue {
 		// Don't bother checking for errors here since hasher panics
 		// if encoding doesn't work and we're not writing to any database.
 		n, _ = t.hasher.replaceChildren(n, nil)
-		hn, _ := t.hasher.store(n, nil, false)
+		hn, _ := t.hasher.store(n, nil, false, nil)
 		if _, ok := hn.(hashNode); ok || i == 0 {
 			// If the node's database encoding is a hash (or is the
 			// root node), it becomes a proof element.
diff --git a/trie/proof_test.go b/trie/proof_test.go
index 6b5bef05c4..0530dff357 100644
--- a/trie/proof_test.go
+++ b/trie/proof_test.go
@@ -119,14 +119,14 @@ func randomTrie(n int) (*Trie, map[string]*kv) {
 	for i := byte(0); i < 100; i++ {
 		value := &kv{common.LeftPadBytes([]byte{i}, 32), []byte{i}, false}
 		value2 := &kv{common.LeftPadBytes([]byte{i + 10}, 32), []byte{i}, false}
-		trie.Update(value.k, value.v)
-		trie.Update(value2.k, value2.v)
+		trie.UpdateIndexed(value.k, value.v, nil)
+		trie.UpdateIndexed(value2.k, value2.v, nil)
 		vals[string(value.k)] = value
 		vals[string(value2.k)] = value2
 	}
 	for i := 0; i < n; i++ {
 		value := &kv{randBytes(32), randBytes(20), false}
-		trie.Update(value.k, value.v)
+		trie.UpdateIndexed(value.k, value.v, nil)
 		vals[string(value.k)] = value
 	}
 	return trie, vals
diff --git a/trie/secure_trie.go b/trie/secure_trie.go
index fb5f694d8e..aabffb40f7 100644
--- a/trie/secure_trie.go
+++ b/trie/secure_trie.go
@@ -79,36 +79,6 @@ func (t *SecureTrie) TryGet(key []byte) ([]byte, error) {
 	return t.Trie.TryGet(t.hashKey(key))
 }
 
-// Update associates key with value in the trie. Subsequent calls to
-// Get will return value. If value has length zero, any existing value
-// is deleted from the trie and calls to Get will return nil.
-//
-// The value bytes must not be modified by the caller while they are
-// stored in the trie.
-func (t *SecureTrie) Update(key, value []byte) {
-	if err := t.TryUpdate(key, value); err != nil && glog.V(logger.Error) {
-		glog.Errorf("Unhandled trie error: %v", err)
-	}
-}
-
-// TryUpdate associates key with value in the trie. Subsequent calls to
-// Get will return value. If value has length zero, any existing value
-// is deleted from the trie and calls to Get will return nil.
-//
-// The value bytes must not be modified by the caller while they are
-// stored in the trie.
-//
-// If a node was not found in the database, a MissingNodeError is returned.
-func (t *SecureTrie) TryUpdate(key, value []byte) error {
-	hk := t.hashKey(key)
-	err := t.Trie.TryUpdate(hk, value)
-	if err != nil {
-		return err
-	}
-	t.Trie.db.Put(t.secKey(hk), key)
-	return nil
-}
-
 // UpdateIndexed is an extended version of Update, where state trie index entries
 // are also generated for all entities referencing the current node.
 //
diff --git a/trie/secure_trie_test.go b/trie/secure_trie_test.go
index 13c6cd02e9..59ee267efc 100644
--- a/trie/secure_trie_test.go
+++ b/trie/secure_trie_test.go
@@ -45,7 +45,7 @@ func TestSecureDelete(t *testing.T) {
 	}
 	for _, val := range vals {
 		if val.v != "" {
-			trie.Update([]byte(val.k), []byte(val.v))
+			trie.UpdateIndexed([]byte(val.k), []byte(val.v), nil)
 		} else {
 			trie.Delete([]byte(val.k))
 		}
@@ -59,7 +59,7 @@ func TestSecureDelete(t *testing.T) {
 
 func TestSecureGetKey(t *testing.T) {
 	trie := newEmptySecure()
-	trie.Update([]byte("foo"), []byte("bar"))
+	trie.UpdateIndexed([]byte("foo"), []byte("bar"), nil)
 
 	key := []byte("foo")
 	value := []byte("bar")
diff --git a/trie/sync.go b/trie/sync.go
index c3cd36cf79..e9955cfb74 100644
--- a/trie/sync.go
+++ b/trie/sync.go
@@ -34,7 +34,7 @@ type request struct {
 	depth   int        // Depth level within the trie the node is located to prioritise DFS
 	deps    int        // Number of dependencies before allowed to commit this node
 
-	externals []common.Hash // External children of this node to index in addition to internal ones
+	referrers []common.Hash // External parents of this node to index in addition to internal ones
 
 	callback TrieSyncLeafCallback // Callback to invoke if a leaf node it reached on this branch
 }
@@ -61,13 +61,13 @@ type TrieSync struct {
 }
 
 // NewTrieSync creates a new trie data download scheduler.
-func NewTrieSync(root common.Hash, database ethdb.Database, callback TrieSyncLeafCallback) *TrieSync {
+func NewTrieSync(root common.Hash, database ethdb.Database, parent common.Hash, callback TrieSyncLeafCallback) *TrieSync {
 	ts := &TrieSync{
 		database: database,
 		requests: make(map[common.Hash]*request),
 		queue:    prque.New(),
 	}
-	ts.AddSubTrie(root, 0, common.Hash{}, callback)
+	ts.AddSubTrie(root, 0, parent, callback)
 	return ts
 }
 
@@ -91,13 +91,15 @@ func (s *TrieSync) AddSubTrie(root common.Hash, depth int, parent common.Hash, c
 	}
 	// If this sub-trie has a designated parent, link them together
 	if parent != (common.Hash{}) {
-		ancestor := s.requests[parent]
-		if ancestor == nil {
-			panic(fmt.Sprintf("sub-trie ancestor not found: %x", parent))
+		if depth > 0 {
+			ancestor := s.requests[parent]
+			if ancestor == nil {
+				panic(fmt.Sprintf("sub-trie ancestor not found: %x", parent))
+			}
+			ancestor.deps++
+			req.parents = append(req.parents, ancestor)
 		}
-		ancestor.deps++
-		ancestor.externals = append(ancestor.externals, root)
-		req.parents = append(req.parents, ancestor)
+		req.referrers = append(req.referrers, parent)
 	}
 	s.schedule(req)
 }
@@ -121,13 +123,15 @@ func (s *TrieSync) AddRawEntry(hash common.Hash, depth int, parent common.Hash)
 	}
 	// If this sub-trie has a designated parent, link them together
 	if parent != (common.Hash{}) {
-		ancestor := s.requests[parent]
-		if ancestor == nil {
-			panic(fmt.Sprintf("raw-entry ancestor not found: %x", parent))
+		if depth > 0 {
+			ancestor := s.requests[parent]
+			if ancestor == nil {
+				panic(fmt.Sprintf("raw-entry ancestor not found: %x", parent))
+			}
+			ancestor.deps++
+			req.parents = append(req.parents, ancestor)
 		}
-		ancestor.deps++
-		ancestor.externals = append(ancestor.externals, hash)
-		req.parents = append(req.parents, ancestor)
+		req.referrers = append(req.referrers, parent)
 	}
 	s.schedule(req)
 }
@@ -276,8 +280,8 @@ func (s *TrieSync) commit(req *request, batch ethdb.Batch) (err error) {
 			return err
 		}
 	}
-	for _, ext := range req.externals {
-		if err := storeParentReferenceEntry(req.hash[:], ext[:], batch); err != nil {
+	for _, referrer := range req.referrers {
+		if err := storeParentReferenceEntry(referrer[:], req.hash[:], batch); err != nil {
 			return err
 		}
 	}
diff --git a/trie/sync_test.go b/trie/sync_test.go
index 6738427bfb..37ccc416a7 100644
--- a/trie/sync_test.go
+++ b/trie/sync_test.go
@@ -26,7 +26,7 @@ import (
 )
 
 // makeTestTrie create a sample test trie to test node-wise reconstruction.
-func makeTestTrie() (ethdb.Database, *Trie, map[string][]byte) {
+func makeTestTrie(referrers [][]byte) (ethdb.Database, *Trie, map[string][]byte) {
 	// Create an empty trie
 	db, _ := ethdb.NewMemDatabase()
 	trie, _ := New(common.Hash{}, db)
@@ -37,20 +37,20 @@ func makeTestTrie() (ethdb.Database, *Trie, map[string][]byte) {
 		// Map the same data under multiple keys
 		key, val := common.LeftPadBytes([]byte{1, i}, 32), []byte{i}
 		content[string(key)] = val
-		trie.Update(key, val)
+		trie.UpdateIndexed(key, val, nil)
 
 		key, val = common.LeftPadBytes([]byte{2, i}, 32), []byte{i}
 		content[string(key)] = val
-		trie.Update(key, val)
+		trie.UpdateIndexed(key, val, nil)
 
 		// Add some other data to inflate th trie
 		for j := byte(3); j < 13; j++ {
 			key, val = common.LeftPadBytes([]byte{j, i}, 32), []byte{j, i}
 			content[string(key)] = val
-			trie.Update(key, val)
+			trie.UpdateIndexed(key, val, nil)
 		}
 	}
-	trie.Commit()
+	trie.CommitIndexed(referrers)
 
 	// Remove any potentially cached data from the test trie creation
 	globalCache.Clear()
@@ -61,7 +61,7 @@ func makeTestTrie() (ethdb.Database, *Trie, map[string][]byte) {
 
 // checkTrieContents cross references a reconstructed trie with an expected data
 // content map.
-func checkTrieContents(t *testing.T, db Database, root []byte, content map[string][]byte) {
+func checkTrieContents(t *testing.T, db Database, root []byte, content map[string][]byte, parent common.Hash) {
 	// Remove any potentially cached data from the trie synchronisation
 	globalCache.Clear()
 
@@ -73,7 +73,7 @@ func checkTrieContents(t *testing.T, db Database, root []byte, content map[strin
 	if err := checkTrieConsistency(db, common.BytesToHash(root)); err != nil {
 		t.Fatalf("inconsistent trie at %x: %v", root, err)
 	}
-	if err := checkTrieIndex(db, common.BytesToHash(root)); err != nil {
+	if err := checkTrieIndex(db, common.BytesToHash(root), parent); err != nil {
 		t.Fatalf("index error at %x: %v", root, err)
 	}
 	for key, val := range content {
@@ -106,20 +106,34 @@ func checkTrieConsistency(db Database, root common.Hash) (failure error) {
 
 // checkTrieIndex iterates over the entire state trie and checks that all required
 // database indexes have been generated by the synchronizer.
-func checkTrieIndex(db Database, root common.Hash) error {
+func checkTrieIndex(db Database, root common.Hash, parent common.Hash) error {
 	// Remove any potentially cached data from the test trie creation or previous checks
 	globalCache.Clear()
 
-	// Create and iterate a trie
 	trie, err := New(root, db)
 	if err != nil {
 		return err
 	}
+	// Gather all the indexes that should be present in the database
+	indexes := make(map[string]struct{})
 	for it := NewNodeIterator(trie); it.Next(); {
 		if (it.Hash != common.Hash{}) && (it.Parent != common.Hash{}) {
-			parentRef := ParentReferenceIndexKey(it.Parent.Bytes(), it.Hash.Bytes())
-			if _, err := db.Get(parentRef); err != nil {
-				return fmt.Errorf("parent reference lookup %x: %v", parentRef, err)
+			indexes[string(ParentReferenceIndexKey(it.Parent.Bytes(), it.Hash.Bytes()))] = struct{}{}
+		}
+	}
+	if parent != (common.Hash{}) {
+		indexes[string(ParentReferenceIndexKey(parent.Bytes(), trie.Hash().Bytes()))] = struct{}{}
+	}
+	// Cross check the indexes and the database itself
+	for index, _ := range indexes {
+		if _, err := db.Get([]byte(index)); err != nil {
+			return fmt.Errorf("failed to retrieve reported index %x: %v", index, err)
+		}
+	}
+	for _, key := range db.(*ethdb.MemDatabase).Keys() {
+		if bytes.HasPrefix(key, ParentReferenceIndexPrefix) {
+			if _, ok := indexes[string(key)]; !ok {
+				return fmt.Errorf("index entry not reported %x", key)
 			}
 		}
 	}
@@ -127,13 +141,18 @@ func checkTrieIndex(db Database, root common.Hash) error {
 }
 
 // Tests that an empty trie is not scheduled for syncing.
-func TestEmptyTrieSync(t *testing.T) {
+func TestEmptyTrieSyncDangling(t *testing.T) { testEmptyTrieSync(t, common.Hash{}) }
+func TestEmptyTrieSyncRooted(t *testing.T) {
+	testEmptyTrieSync(t, common.BytesToHash([]byte{0x01}))
+}
+
+func testEmptyTrieSync(t *testing.T, origin common.Hash) {
 	emptyA, _ := New(common.Hash{}, nil)
 	emptyB, _ := New(emptyRoot, nil)
 
 	for i, trie := range []*Trie{emptyA, emptyB} {
 		db, _ := ethdb.NewMemDatabase()
-		if req := NewTrieSync(common.BytesToHash(trie.Root()), db, nil).Missing(1); len(req) != 0 {
+		if req := NewTrieSync(common.BytesToHash(trie.Root()), db, origin, nil).Missing(1); len(req) != 0 {
 			t.Errorf("test %d: content requested for empty trie: %v", i, req)
 		}
 	}
@@ -141,16 +160,26 @@ func TestEmptyTrieSync(t *testing.T) {
 
 // Tests that given a root hash, a trie can sync iteratively on a single thread,
 // requesting retrieval tasks and returning all of them in one go.
-func TestIterativeTrieSyncIndividual(t *testing.T) { testIterativeTrieSync(t, 1) }
-func TestIterativeTrieSyncBatched(t *testing.T)    { testIterativeTrieSync(t, 100) }
+func TestIterativeTrieSyncIndividualDangling(t *testing.T) {
+	testIterativeTrieSync(t, 1, common.Hash{})
+}
+func TestIterativeTrieSyncIndividualRooted(t *testing.T) {
+	testIterativeTrieSync(t, 1, common.BytesToHash([]byte{0x02}))
+}
+func TestIterativeTrieSyncBatchedDangling(t *testing.T) {
+	testIterativeTrieSync(t, 100, common.Hash{})
+}
+func TestIterativeTrieSyncBatchedRooted(t *testing.T) {
+	testIterativeTrieSync(t, 100, common.BytesToHash([]byte{0x03}))
+}
 
-func testIterativeTrieSync(t *testing.T, batch int) {
+func testIterativeTrieSync(t *testing.T, batch int, origin common.Hash) {
 	// Create a random trie to copy
-	srcDb, srcTrie, srcData := makeTestTrie()
+	srcDb, srcTrie, srcData := makeTestTrie(nil)
 
 	// Create a destination trie and sync with the scheduler
 	dstDb, _ := ethdb.NewMemDatabase()
-	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, nil)
+	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, origin, nil)
 
 	queue := append([]common.Hash{}, sched.Missing(batch)...)
 	for len(queue) > 0 {
@@ -168,18 +197,25 @@ func testIterativeTrieSync(t *testing.T, batch int) {
 		queue = append(queue[:0], sched.Missing(batch)...)
 	}
 	// Cross check that the two tries are in sync
-	checkTrieContents(t, dstDb, srcTrie.Root(), srcData)
+	checkTrieContents(t, dstDb, srcTrie.Root(), srcData, origin)
 }
 
 // Tests that the trie scheduler can correctly reconstruct the state even if only
 // partial results are returned, and the others sent only later.
-func TestIterativeDelayedTrieSync(t *testing.T) {
+func TestIterativeDelayedTrieSyncDangling(t *testing.T) {
+	testIterativeDelayedTrieSync(t, common.Hash{})
+}
+func TestIterativeDelayedTrieSyncRooted(t *testing.T) {
+	testIterativeDelayedTrieSync(t, common.BytesToHash([]byte{0x04}))
+}
+
+func testIterativeDelayedTrieSync(t *testing.T, origin common.Hash) {
 	// Create a random trie to copy
-	srcDb, srcTrie, srcData := makeTestTrie()
+	srcDb, srcTrie, srcData := makeTestTrie(nil)
 
 	// Create a destination trie and sync with the scheduler
 	dstDb, _ := ethdb.NewMemDatabase()
-	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, nil)
+	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, origin, nil)
 
 	queue := append([]common.Hash{}, sched.Missing(10000)...)
 	for len(queue) > 0 {
@@ -198,22 +234,32 @@ func TestIterativeDelayedTrieSync(t *testing.T) {
 		queue = append(queue[len(results):], sched.Missing(10000)...)
 	}
 	// Cross check that the two tries are in sync
-	checkTrieContents(t, dstDb, srcTrie.Root(), srcData)
+	checkTrieContents(t, dstDb, srcTrie.Root(), srcData, origin)
 }
 
 // Tests that given a root hash, a trie can sync iteratively on a single thread,
 // requesting retrieval tasks and returning all of them in one go, however in a
 // random order.
-func TestIterativeRandomTrieSyncIndividual(t *testing.T) { testIterativeRandomTrieSync(t, 1) }
-func TestIterativeRandomTrieSyncBatched(t *testing.T)    { testIterativeRandomTrieSync(t, 100) }
+func TestIterativeRandomTrieSyncIndividualDangling(t *testing.T) {
+	testIterativeRandomTrieSync(t, 1, common.Hash{})
+}
+func TestIterativeRandomTrieSyncIndividualRooted(t *testing.T) {
+	testIterativeRandomTrieSync(t, 1, common.BytesToHash([]byte{0x05}))
+}
+func TestIterativeRandomTrieSyncBatchedDangling(t *testing.T) {
+	testIterativeRandomTrieSync(t, 100, common.Hash{})
+}
+func TestIterativeRandomTrieSyncBatchedlRooted(t *testing.T) {
+	testIterativeRandomTrieSync(t, 100, common.BytesToHash([]byte{0x06}))
+}
 
-func testIterativeRandomTrieSync(t *testing.T, batch int) {
+func testIterativeRandomTrieSync(t *testing.T, batch int, origin common.Hash) {
 	// Create a random trie to copy
-	srcDb, srcTrie, srcData := makeTestTrie()
+	srcDb, srcTrie, srcData := makeTestTrie(nil)
 
 	// Create a destination trie and sync with the scheduler
 	dstDb, _ := ethdb.NewMemDatabase()
-	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, nil)
+	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, origin, nil)
 
 	queue := make(map[common.Hash]struct{})
 	for _, hash := range sched.Missing(batch) {
@@ -239,18 +285,25 @@ func testIterativeRandomTrieSync(t *testing.T, batch int) {
 		}
 	}
 	// Cross check that the two tries are in sync
-	checkTrieContents(t, dstDb, srcTrie.Root(), srcData)
+	checkTrieContents(t, dstDb, srcTrie.Root(), srcData, origin)
 }
 
 // Tests that the trie scheduler can correctly reconstruct the state even if only
 // partial results are returned (Even those randomly), others sent only later.
-func TestIterativeRandomDelayedTrieSync(t *testing.T) {
+func TestIterativeRandomDelayedTrieSyncDangling(t *testing.T) {
+	testIterativeRandomDelayedTrieSync(t, common.Hash{})
+}
+func TestIterativeRandomDelayedTrieSyncRooted(t *testing.T) {
+	testIterativeRandomDelayedTrieSync(t, common.BytesToHash([]byte{0x07}))
+}
+
+func testIterativeRandomDelayedTrieSync(t *testing.T, origin common.Hash) {
 	// Create a random trie to copy
-	srcDb, srcTrie, srcData := makeTestTrie()
+	srcDb, srcTrie, srcData := makeTestTrie(nil)
 
 	// Create a destination trie and sync with the scheduler
 	dstDb, _ := ethdb.NewMemDatabase()
-	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, nil)
+	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, origin, nil)
 
 	queue := make(map[common.Hash]struct{})
 	for _, hash := range sched.Missing(10000) {
@@ -282,18 +335,25 @@ func TestIterativeRandomDelayedTrieSync(t *testing.T) {
 		}
 	}
 	// Cross check that the two tries are in sync
-	checkTrieContents(t, dstDb, srcTrie.Root(), srcData)
+	checkTrieContents(t, dstDb, srcTrie.Root(), srcData, origin)
 }
 
 // Tests that a trie sync will not request nodes multiple times, even if they
 // have such references.
-func TestDuplicateAvoidanceTrieSync(t *testing.T) {
+func TestDuplicateAvoidanceTrieSyncDangling(t *testing.T) {
+	testDuplicateAvoidanceTrieSync(t, common.Hash{})
+}
+func TestDuplicateAvoidanceTrieSyncRooted(t *testing.T) {
+	testDuplicateAvoidanceTrieSync(t, common.BytesToHash([]byte{0x08}))
+}
+
+func testDuplicateAvoidanceTrieSync(t *testing.T, origin common.Hash) {
 	// Create a random trie to copy
-	srcDb, srcTrie, srcData := makeTestTrie()
+	srcDb, srcTrie, srcData := makeTestTrie(nil)
 
 	// Create a destination trie and sync with the scheduler
 	dstDb, _ := ethdb.NewMemDatabase()
-	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, nil)
+	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, origin, nil)
 
 	queue := append([]common.Hash{}, sched.Missing(0)...)
 	requested := make(map[common.Hash]struct{})
@@ -318,18 +378,18 @@ func TestDuplicateAvoidanceTrieSync(t *testing.T) {
 		queue = append(queue[:0], sched.Missing(0)...)
 	}
 	// Cross check that the two tries are in sync
-	checkTrieContents(t, dstDb, srcTrie.Root(), srcData)
+	checkTrieContents(t, dstDb, srcTrie.Root(), srcData, origin)
 }
 
 // Tests that at any point in time during a sync, only complete sub-tries are in
 // the database.
 func TestIncompleteTrieSync(t *testing.T) {
 	// Create a random trie to copy
-	srcDb, srcTrie, _ := makeTestTrie()
+	srcDb, srcTrie, _ := makeTestTrie(nil)
 
 	// Create a destination trie and sync with the scheduler
 	dstDb, _ := ethdb.NewMemDatabase()
-	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, nil)
+	sched := NewTrieSync(common.BytesToHash(srcTrie.Root()), dstDb, common.Hash{}, nil)
 
 	added := []common.Hash{}
 	queue := append([]common.Hash{}, sched.Missing(1)...)
diff --git a/trie/trie.go b/trie/trie.go
index 88b32aa45a..97cf624075 100644
--- a/trie/trie.go
+++ b/trie/trie.go
@@ -146,50 +146,30 @@ func (t *Trie) TryGet(key []byte) ([]byte, error) {
 	return tn.(valueNode).Value, nil
 }
 
-// Update associates key with value in the trie. Subsequent calls to
-// Get will return value. If value has length zero, any existing value
-// is deleted from the trie and calls to Get will return nil.
+// UpdateIndexed associates key with value in the trie. Subsequent calls to Get
+// will return value. If value has length zero, any existing value is deleted
+// from the trie and calls to Get will return nil. In addition, state trie index
+// entries are also generated for all entities referencing the current node.
 //
 // The value bytes must not be modified by the caller while they are
 // stored in the trie.
-func (t *Trie) Update(key, value []byte) {
-	if err := t.TryUpdate(key, value); err != nil && glog.V(logger.Error) {
+func (t *Trie) UpdateIndexed(key, value []byte, references [][]byte) {
+	if err := t.TryUpdateIndexed(key, value, references); err != nil && glog.V(logger.Error) {
 		glog.Errorf("Unhandled trie error: %v", err)
 	}
 }
 
-// TryUpdate associates key with value in the trie. Subsequent calls to
-// Get will return value. If value has length zero, any existing value
-// is deleted from the trie and calls to Get will return nil.
-//
-// The value bytes must not be modified by the caller while they are
-// stored in the trie.
-//
-// If a node was not found in the database, a MissingNodeError is returned.
-func (t *Trie) TryUpdate(key, value []byte) error {
-	return t.tryUpdateIndexed(key, value, nil)
-}
-
-// UpdateIndexed is an extended version of Update, where state trie index entries
-// are also generated for all entities referencing the current node.
-//
-// The value bytes must not be modified by the caller while they are
-// stored in the trie.
-func (t *Trie) UpdateIndexed(key, value []byte, refs [][]byte) {
-	if err := t.TryUpdateIndexed(key, value, refs); err != nil && glog.V(logger.Error) {
-		glog.Errorf("Unhandled trie error: %v", err)
-	}
-}
-
-// TryUpdateIndexed is an extended version of Update, where state trie index
+// TryUpdateIndexed associates key with value in the trie. Subsequent calls to
+// Get will return value. If value has length zero, any existing value is deleted
+// from the trie and calls to Get will return nil. In addition, state trie index
 // entries are also generated for all entities referencing the current node.
 //
 // The value bytes must not be modified by the caller while they are
 // stored in the trie.
 //
 // If a node was not found in the database, a MissingNodeError is returned.
-func (t *Trie) TryUpdateIndexed(key, value []byte, refs [][]byte) error {
-	return t.tryUpdateIndexed(key, value, refs)
+func (t *Trie) TryUpdateIndexed(key, value []byte, references [][]byte) error {
+	return t.tryUpdateIndexed(key, value, references)
 }
 
 func (t *Trie) tryUpdateIndexed(key, value []byte, refs [][]byte) error {
@@ -439,31 +419,32 @@ func (t *Trie) Root() []byte { return t.Hash().Bytes() }
 // Hash returns the root hash of the trie. It does not write to the
 // database and can be used even if the trie doesn't have one.
 func (t *Trie) Hash() common.Hash {
-	root, _ := t.hashRoot(nil)
+	root, _ := t.hashRoot(nil, nil)
 	return common.BytesToHash(root.(hashNode))
 }
 
-// Commit writes all nodes to the trie's database.
-// Nodes are stored with their sha3 hash as the key.
+// CommitIndexed writes all nodes to the trie's database, and if any references
+// were specified, adds those to the trie index as well. Nodes are stored with
+// their sha3 hash as the key.
 //
-// Committing flushes nodes from memory.
-// Subsequent Get calls will load nodes from the database.
-func (t *Trie) Commit() (root common.Hash, err error) {
+// Committing flushes nodes from memory. Subsequent Get calls will load nodes
+// from the database.
+func (t *Trie) CommitIndexed(referrers [][]byte) (root common.Hash, err error) {
 	if t.db == nil {
 		panic("Commit called on trie with nil database")
 	}
-	return t.CommitTo(t.db)
+	return t.CommitToIndexed(t.db, referrers)
 }
 
-// CommitTo writes all nodes to the given database.
-// Nodes are stored with their sha3 hash as the key.
+// CommitToIndexed writes all nodes to the given database, and if any references
+// were specified, adds those to the trie index as well. Nodes are stored with
+// their sha3 hash as the key.
 //
-// Committing flushes nodes from memory. Subsequent Get calls will
-// load nodes from the trie's database. Calling code must ensure that
-// the changes made to db are written back to the trie's attached
-// database before using the trie.
-func (t *Trie) CommitTo(db DatabaseWriter) (root common.Hash, err error) {
-	n, err := t.hashRoot(db)
+// Committing flushes nodes from memory. Subsequent Get calls will load nodes
+// from the trie's database. Calling code must ensure that the changes made to
+// db are written back to the trie's attached database before using the trie.
+func (t *Trie) CommitToIndexed(db DatabaseWriter, referrers [][]byte) (root common.Hash, err error) {
+	n, err := t.hashRoot(db, referrers)
 	if err != nil {
 		return (common.Hash{}), err
 	}
@@ -471,14 +452,14 @@ func (t *Trie) CommitTo(db DatabaseWriter) (root common.Hash, err error) {
 	return common.BytesToHash(n.(hashNode)), nil
 }
 
-func (t *Trie) hashRoot(db DatabaseWriter) (node, error) {
+func (t *Trie) hashRoot(db DatabaseWriter, referrers [][]byte) (node, error) {
 	if t.root == nil {
 		return hashNode(emptyRoot.Bytes()), nil
 	}
 	if t.hasher == nil {
 		t.hasher = newHasher()
 	}
-	return t.hasher.hash(t.root, db, true)
+	return t.hasher.hash(t.root, db, true, referrers)
 }
 
 type hasher struct {
@@ -490,12 +471,12 @@ func newHasher() *hasher {
 	return &hasher{tmp: new(bytes.Buffer), sha: sha3.NewKeccak256()}
 }
 
-func (h *hasher) hash(n node, db DatabaseWriter, force bool) (node, error) {
+func (h *hasher) hash(n node, db DatabaseWriter, force bool, referrers [][]byte) (node, error) {
 	hashed, err := h.replaceChildren(n, db)
 	if err != nil {
 		return hashNode{}, err
 	}
-	if n, err = h.store(hashed, db, force); err != nil {
+	if n, err = h.store(hashed, db, force, referrers); err != nil {
 		return hashNode{}, err
 	}
 	return n, nil
@@ -509,7 +490,7 @@ func (h *hasher) replaceChildren(n node, db DatabaseWriter) (node, error) {
 	case shortNode:
 		n.Key = compactEncode(n.Key)
 		if _, ok := n.Val.(valueNode); !ok {
-			if n.Val, err = h.hash(n.Val, db, false); err != nil {
+			if n.Val, err = h.hash(n.Val, db, false, nil); err != nil {
 				return n, err
 			}
 		}
@@ -521,7 +502,7 @@ func (h *hasher) replaceChildren(n node, db DatabaseWriter) (node, error) {
 	case fullNode:
 		for i := 0; i < 16; i++ {
 			if n[i] != nil {
-				if n[i], err = h.hash(n[i], db, false); err != nil {
+				if n[i], err = h.hash(n[i], db, false, nil); err != nil {
 					return n, err
 				}
 			} else {
@@ -538,7 +519,7 @@ func (h *hasher) replaceChildren(n node, db DatabaseWriter) (node, error) {
 	}
 }
 
-func (h *hasher) store(n node, db DatabaseWriter, force bool) (node, error) {
+func (h *hasher) store(n node, db DatabaseWriter, force bool, referrers [][]byte) (node, error) {
 	// Don't store hashes or empty nodes.
 	if _, isHash := n.(hashNode); n == nil || isHash {
 		return n, nil
@@ -559,6 +540,11 @@ func (h *hasher) store(n node, db DatabaseWriter, force bool) (node, error) {
 		if err := storeParentReferences(key, n, db); err != nil {
 			return key, err
 		}
+		for _, referrer := range referrers {
+			if err := storeParentReferenceEntry(referrer, key, db); err != nil {
+				return key, err
+			}
+		}
 		if err := db.Put(key, h.tmp.Bytes()); err != nil {
 			return key, err
 		}
diff --git a/trie/trie_test.go b/trie/trie_test.go
index 35d043cdf1..244f5d28d5 100644
--- a/trie/trie_test.go
+++ b/trie/trie_test.go
@@ -54,7 +54,7 @@ func TestNull(t *testing.T) {
 	var trie Trie
 	key := make([]byte, 32)
 	value := common.FromHex("0x823140710bf13990e4500136726d8b55")
-	trie.Update(key, value)
+	trie.UpdateIndexed(key, value, nil)
 	value = trie.Get(key)
 }
 
@@ -74,7 +74,7 @@ func TestMissingNode(t *testing.T) {
 	trie, _ := New(common.Hash{}, db)
 	updateString(trie, "120000", "qwerqwerqwerqwerqwerqwerqwerqwer")
 	updateString(trie, "123456", "asdfasdfasdfasdfasdfasdfasdfasdf")
-	root, _ := trie.Commit()
+	root, _ := trie.CommitIndexed(nil)
 
 	ClearGlobalCache()
 
@@ -97,7 +97,7 @@ func TestMissingNode(t *testing.T) {
 	}
 
 	trie, _ = New(root, db)
-	err = trie.TryUpdate([]byte("120099"), []byte("zxcvzxcvzxcvzxcvzxcvzxcvzxcvzxcv"))
+	err = trie.TryUpdateIndexed([]byte("120099"), []byte("zxcvzxcvzxcvzxcvzxcvzxcvzxcvzxcv"), nil)
 	if err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	}
@@ -130,7 +130,7 @@ func TestMissingNode(t *testing.T) {
 	}
 
 	trie, _ = New(root, db)
-	err = trie.TryUpdate([]byte("120099"), []byte("zxcv"))
+	err = trie.TryUpdateIndexed([]byte("120099"), []byte("zxcv"), nil)
 	if _, ok := err.(*MissingNodeError); !ok {
 		t.Errorf("Wrong error: %v", err)
 	}
@@ -159,7 +159,7 @@ func TestInsert(t *testing.T) {
 	updateString(trie, "A", "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
 
 	exp = common.HexToHash("d23786fb4a010da3ce639d66d5e904a11dbc02746d1ce25029e53290cabf28ab")
-	root, err := trie.Commit()
+	root, err := trie.CommitIndexed(nil)
 	if err != nil {
 		t.Fatalf("commit error: %v", err)
 	}
@@ -188,7 +188,7 @@ func TestGet(t *testing.T) {
 		if i == 1 {
 			return
 		}
-		trie.Commit()
+		trie.CommitIndexed(nil)
 	}
 }
 
@@ -257,7 +257,7 @@ func TestReplication(t *testing.T) {
 	for _, val := range vals {
 		updateString(trie, val.k, val.v)
 	}
-	exp, err := trie.Commit()
+	exp, err := trie.CommitIndexed(nil)
 	if err != nil {
 		t.Fatalf("commit error: %v", err)
 	}
@@ -272,7 +272,7 @@ func TestReplication(t *testing.T) {
 			t.Errorf("trie2 doesn't have %q => %q", kv.k, kv.v)
 		}
 	}
-	hash, err := trie2.Commit()
+	hash, err := trie2.CommitIndexed(nil)
 	if err != nil {
 		t.Fatalf("commit error: %v", err)
 	}
@@ -304,7 +304,7 @@ func paranoiaCheck(t1 *Trie) (bool, *Trie) {
 	t2 := new(Trie)
 	it := NewIterator(t1)
 	for it.Next() {
-		t2.Update(it.Key, it.Value)
+		t2.UpdateIndexed(it.Key, it.Value, nil)
 	}
 	return t2.Hash() == t1.Hash(), t2
 }
@@ -327,7 +327,7 @@ func TestParanoia(t *testing.T) {
 	for _, val := range vals {
 		updateString(trie, val.k, val.v)
 	}
-	trie.Commit()
+	trie.CommitIndexed(nil)
 
 	ok, t2 := paranoiaCheck(trie)
 	if !ok {
@@ -347,7 +347,7 @@ func TestOutput(t *testing.T) {
 	fmt.Println("############################## FULL ################################")
 	fmt.Println(trie.root)
 
-	trie.Commit()
+	trie.CommitIndexed(nil)
 	fmt.Println("############################## SMALL ################################")
 	trie2, _ := New(trie.Hash(), trie.db)
 	getString(trie2, base+"20")
@@ -356,8 +356,8 @@ func TestOutput(t *testing.T) {
 
 func TestLargeValue(t *testing.T) {
 	trie := newEmpty()
-	trie.Update([]byte("key1"), []byte{99, 99, 99, 99})
-	trie.Update([]byte("key2"), bytes.Repeat([]byte{1}, 32))
+	trie.UpdateIndexed([]byte("key1"), []byte{99, 99, 99, 99}, nil)
+	trie.UpdateIndexed([]byte("key2"), bytes.Repeat([]byte{1}, 32), nil)
 	trie.Hash()
 
 }
@@ -374,8 +374,8 @@ func TestLargeData(t *testing.T) {
 	for i := byte(0); i < 255; i++ {
 		value := &kv{common.LeftPadBytes([]byte{i}, 32), []byte{i}, false}
 		value2 := &kv{common.LeftPadBytes([]byte{10, i}, 32), []byte{i}, false}
-		trie.Update(value.k, value.v)
-		trie.Update(value2.k, value2.v)
+		trie.UpdateIndexed(value.k, value.v, nil)
+		trie.UpdateIndexed(value2.k, value2.v, nil)
 		vals[string(value.k)] = value
 		vals[string(value2.k)] = value2
 	}
@@ -419,11 +419,11 @@ func benchGet(b *testing.B, commit bool) {
 	k := make([]byte, 32)
 	for i := 0; i < benchElemCount; i++ {
 		binary.LittleEndian.PutUint64(k, uint64(i))
-		trie.Update(k, k)
+		trie.UpdateIndexed(k, k, nil)
 	}
 	binary.LittleEndian.PutUint64(k, benchElemCount/2)
 	if commit {
-		trie.Commit()
+		trie.CommitIndexed(nil)
 	}
 
 	b.ResetTimer()
@@ -437,7 +437,7 @@ func benchUpdate(b *testing.B, e binary.ByteOrder) *Trie {
 	k := make([]byte, 32)
 	for i := 0; i < b.N; i++ {
 		e.PutUint64(k, uint64(i))
-		trie.Update(k, k)
+		trie.UpdateIndexed(k, k, nil)
 	}
 	return trie
 }
@@ -447,7 +447,7 @@ func benchHash(b *testing.B, e binary.ByteOrder) {
 	k := make([]byte, 32)
 	for i := 0; i < benchElemCount; i++ {
 		e.PutUint64(k, uint64(i))
-		trie.Update(k, k)
+		trie.UpdateIndexed(k, k, nil)
 	}
 
 	b.ResetTimer()
@@ -473,7 +473,7 @@ func getString(trie *Trie, k string) []byte {
 }
 
 func updateString(trie *Trie, k, v string) {
-	trie.Update([]byte(k), []byte(v))
+	trie.UpdateIndexed([]byte(k), []byte(v), nil)
 }
 
 func deleteString(trie *Trie, k string) {