diff --git a/graph/iterator/hasa_iterator.go b/graph/iterator/hasa_iterator.go
index 99dec4f..b88f58b 100644
--- a/graph/iterator/hasa_iterator.go
+++ b/graph/iterator/hasa_iterator.go
@@ -202,8 +202,7 @@ func (it *HasA) Next() bool {
 		return graph.NextLogOut(it, 0, false)
 	}
 	tID := it.primaryIt.Result()
-	name := it.ts.Quad(tID).Get(it.dir)
-	val := it.ts.ValueOf(name)
+	val := it.ts.TripleDirection(tID, it.dir)
 	it.result = val
 	return graph.NextLogOut(it, val, true)
 }
diff --git a/graph/leveldb/iterator.go b/graph/leveldb/iterator.go
index 4a1172c..035224c 100644
--- a/graph/leveldb/iterator.go
+++ b/graph/leveldb/iterator.go
@@ -43,7 +43,7 @@ type Iterator struct {
 
 func NewIterator(prefix string, d quad.Direction, value graph.Value, qs *TripleStore) *Iterator {
 	vb := value.(Token)
-	p := make([]byte, 0, 2+qs.hasher.Size())
+	p := make([]byte, 0, 2+qs.hasher_size)
 	p = append(p, []byte(prefix)...)
 	p = append(p, []byte(vb[1:])...)
 
@@ -169,9 +169,9 @@ func PositionOf(prefix []byte, d quad.Direction, qs *TripleStore) int {
 		case quad.Subject:
 			return 2
 		case quad.Predicate:
-			return qs.hasher.Size() + 2
+			return qs.hasher_size + 2
 		case quad.Object:
-			return 2*qs.hasher.Size() + 2
+			return 2*qs.hasher_size + 2
 		case quad.Label:
 			return -1
 		}
@@ -179,11 +179,11 @@ func PositionOf(prefix []byte, d quad.Direction, qs *TripleStore) int {
 	if bytes.Equal(prefix, []byte("po")) {
 		switch d {
 		case quad.Subject:
-			return 2*qs.hasher.Size() + 2
+			return 2*qs.hasher_size + 2
 		case quad.Predicate:
 			return 2
 		case quad.Object:
-			return qs.hasher.Size() + 2
+			return qs.hasher_size + 2
 		case quad.Label:
 			return -1
 		}
@@ -191,9 +191,9 @@ func PositionOf(prefix []byte, d quad.Direction, qs *TripleStore) int {
 	if bytes.Equal(prefix, []byte("os")) {
 		switch d {
 		case quad.Subject:
-			return qs.hasher.Size() + 2
+			return qs.hasher_size + 2
 		case quad.Predicate:
-			return 2*qs.hasher.Size() + 2
+			return 2*qs.hasher_size + 2
 		case quad.Object:
 			return 2
 		case quad.Label:
@@ -203,11 +203,11 @@ func PositionOf(prefix []byte, d quad.Direction, qs *TripleStore) int {
 	if bytes.Equal(prefix, []byte("cp")) {
 		switch d {
 		case quad.Subject:
-			return 2*qs.hasher.Size() + 2
+			return 2*qs.hasher_size + 2
 		case quad.Predicate:
-			return qs.hasher.Size() + 2
+			return qs.hasher_size + 2
 		case quad.Object:
-			return 3*qs.hasher.Size() + 2
+			return 3*qs.hasher_size + 2
 		case quad.Label:
 			return 2
 		}
diff --git a/graph/leveldb/triplestore.go b/graph/leveldb/triplestore.go
index 7efb03f..71304df 100644
--- a/graph/leveldb/triplestore.go
+++ b/graph/leveldb/triplestore.go
@@ -49,14 +49,15 @@ func (t Token) Key() interface{} {
 }
 
 type TripleStore struct {
-	dbOpts    *opt.Options
-	db        *leveldb.DB
-	path      string
-	open      bool
-	size      int64
-	hasher    hash.Hash
-	writeopts *opt.WriteOptions
-	readopts  *opt.ReadOptions
+	dbOpts      *opt.Options
+	db          *leveldb.DB
+	path        string
+	open        bool
+	size        int64
+	hasher_size int
+	make_hasher func() hash.Hash
+	writeopts   *opt.WriteOptions
+	readopts    *opt.ReadOptions
 }
 
 func createNewLevelDB(path string, _ graph.Options) error {
@@ -93,7 +94,8 @@ func newTripleStore(path string, options graph.Options) (graph.TripleStore, erro
 		write_buffer_mb = val
 	}
 	qs.dbOpts.WriteBuffer = write_buffer_mb * opt.MiB
-	qs.hasher = sha1.New()
+	qs.hasher_size = sha1.Size
+	qs.make_hasher = func() hash.Hash { return sha1.New() }
 	qs.writeopts = &opt.WriteOptions{
 		Sync: false,
 	}
@@ -123,30 +125,33 @@ func (qs *TripleStore) Size() int64 {
 }
 
 func (qs *TripleStore) createKeyFor(d [3]quad.Direction, triple quad.Quad) []byte {
-	key := make([]byte, 0, 2+(qs.hasher.Size()*3))
+	hasher := qs.make_hasher()
+	key := make([]byte, 0, 2+(qs.hasher_size*3))
 	// TODO(kortschak) Remove dependence on String() method.
 	key = append(key, []byte{d[0].Prefix(), d[1].Prefix()}...)
-	key = append(key, qs.convertStringToByteHash(triple.Get(d[0]))...)
-	key = append(key, qs.convertStringToByteHash(triple.Get(d[1]))...)
-	key = append(key, qs.convertStringToByteHash(triple.Get(d[2]))...)
+	key = append(key, qs.convertStringToByteHash(triple.Get(d[0]), hasher)...)
+	key = append(key, qs.convertStringToByteHash(triple.Get(d[1]), hasher)...)
+	key = append(key, qs.convertStringToByteHash(triple.Get(d[2]), hasher)...)
 	return key
 }
 
 func (qs *TripleStore) createProvKeyFor(d [3]quad.Direction, triple quad.Quad) []byte {
-	key := make([]byte, 0, 2+(qs.hasher.Size()*4))
+	hasher := qs.make_hasher()
+	key := make([]byte, 0, 2+(qs.hasher_size*4))
 	// TODO(kortschak) Remove dependence on String() method.
 	key = append(key, []byte{quad.Label.Prefix(), d[0].Prefix()}...)
-	key = append(key, qs.convertStringToByteHash(triple.Get(quad.Label))...)
-	key = append(key, qs.convertStringToByteHash(triple.Get(d[0]))...)
-	key = append(key, qs.convertStringToByteHash(triple.Get(d[1]))...)
-	key = append(key, qs.convertStringToByteHash(triple.Get(d[2]))...)
+	key = append(key, qs.convertStringToByteHash(triple.Get(quad.Label), hasher)...)
+	key = append(key, qs.convertStringToByteHash(triple.Get(d[0]), hasher)...)
+	key = append(key, qs.convertStringToByteHash(triple.Get(d[1]), hasher)...)
+	key = append(key, qs.convertStringToByteHash(triple.Get(d[2]), hasher)...)
 	return key
 }
 
 func (qs *TripleStore) createValueKeyFor(s string) []byte {
-	key := make([]byte, 0, 1+qs.hasher.Size())
+	hasher := qs.make_hasher()
+	key := make([]byte, 0, 1+qs.hasher_size)
 	key = append(key, []byte("z")...)
-	key = append(key, qs.convertStringToByteHash(s)...)
+	key = append(key, qs.convertStringToByteHash(s, hasher)...)
 	return key
 }
 
@@ -331,11 +336,11 @@ func (qs *TripleStore) Quad(k graph.Value) quad.Quad {
 	return triple
 }
 
-func (qs *TripleStore) convertStringToByteHash(s string) []byte {
-	qs.hasher.Reset()
-	key := make([]byte, 0, qs.hasher.Size())
-	qs.hasher.Write([]byte(s))
-	key = qs.hasher.Sum(key)
+func (qs *TripleStore) convertStringToByteHash(s string, hasher hash.Hash) []byte {
+	hasher.Reset()
+	key := make([]byte, 0, qs.hasher_size)
+	hasher.Write([]byte(s))
+	key = hasher.Sum(key)
 	return key
 }
 
@@ -441,7 +446,7 @@ func (qs *TripleStore) TripleDirection(val graph.Value, d quad.Direction) graph.
 	v := val.(Token)
 	offset := PositionOf(v[0:2], d, qs)
 	if offset != -1 {
-		return Token(append([]byte("z"), v[offset:offset+qs.hasher.Size()]...))
+		return Token(append([]byte("z"), v[offset:offset+qs.hasher_size]...))
 	} else {
 		return Token(qs.Quad(val).Get(d))
 	}