diff --git a/repository/index.go b/repository/index.go
index d36eb218c..979401a91 100644
--- a/repository/index.go
+++ b/repository/index.go
@@ -26,7 +26,7 @@ type Index struct {
 
 type indexEntry struct {
 	tpe    pack.BlobType
-	packID *backend.ID
+	packID backend.ID
 	offset uint
 	length uint
 }
@@ -39,7 +39,7 @@ func NewIndex() *Index {
 	}
 }
 
-func (idx *Index) store(t pack.BlobType, id backend.ID, pack *backend.ID, offset, length uint) {
+func (idx *Index) store(t pack.BlobType, id backend.ID, pack backend.ID, offset, length uint) {
 	idx.pack[id] = indexEntry{
 		tpe:    t,
 		packID: pack,
@@ -95,7 +95,7 @@ func (idx *Index) Full() bool {
 
 // Store remembers the id and pack in the index. An existing entry will be
 // silently overwritten.
-func (idx *Index) Store(t pack.BlobType, id backend.ID, pack *backend.ID, offset, length uint) {
+func (idx *Index) Store(t pack.BlobType, id backend.ID, pack backend.ID, offset, length uint) {
 	idx.m.Lock()
 	defer idx.m.Unlock()
 
@@ -110,7 +110,7 @@ func (idx *Index) Store(t pack.BlobType, id backend.ID, pack *backend.ID, offset
 }
 
 // Lookup returns the pack for the id.
-func (idx *Index) Lookup(id backend.ID) (packID *backend.ID, tpe pack.BlobType, offset, length uint, err error) {
+func (idx *Index) Lookup(id backend.ID) (packID backend.ID, tpe pack.BlobType, offset, length uint, err error) {
 	idx.m.Lock()
 	defer idx.m.Unlock()
 
@@ -121,7 +121,7 @@ func (idx *Index) Lookup(id backend.ID) (packID *backend.ID, tpe pack.BlobType,
 	}
 
 	debug.Log("Index.Lookup", "id %v not found", id.Str())
-	return nil, pack.Data, 0, 0, fmt.Errorf("id %v not found in index", id)
+	return backend.ID{}, pack.Data, 0, 0, fmt.Errorf("id %v not found in index", id)
 }
 
 // Has returns true iff the id is listed in the index.
@@ -196,7 +196,7 @@ func (idx *Index) Each(done chan struct{}) <-chan PackedBlob {
 					Type:   blob.tpe,
 					Length: blob.length,
 				},
-				PackID: *blob.packID,
+				PackID: blob.packID,
 			}:
 			}
 		}
@@ -239,8 +239,8 @@ func (idx *Index) generatePackList() ([]*packJSON, error) {
 	packs := make(map[backend.ID]*packJSON)
 
 	for id, blob := range idx.pack {
-		if blob.packID == nil {
-			panic("nil pack id")
+		if blob.packID.IsNull() {
+			panic("null pack id")
 		}
 
 		debug.Log("Index.generatePackList", "handle blob %v", id.Str())
@@ -252,10 +252,10 @@ func (idx *Index) generatePackList() ([]*packJSON, error) {
 		}
 
 		// see if pack is already in map
-		p, ok := packs[*blob.packID]
+		p, ok := packs[blob.packID]
 		if !ok {
 			// else create new pack
-			p = &packJSON{ID: *blob.packID}
+			p = &packJSON{ID: blob.packID}
 
 			// and append it to the list and map
 			list = append(list, p)
@@ -380,7 +380,7 @@ func DecodeIndex(rd io.Reader) (idx *Index, err error) {
 	idx = NewIndex()
 	for _, pack := range idxJSON.Packs {
 		for _, blob := range pack.Blobs {
-			idx.store(blob.Type, blob.ID, &pack.ID, blob.Offset, blob.Length)
+			idx.store(blob.Type, blob.ID, pack.ID, blob.Offset, blob.Length)
 		}
 	}
 	idx.supersedes = idxJSON.Supersedes
@@ -405,7 +405,7 @@ func DecodeOldIndex(rd io.Reader) (idx *Index, err error) {
 	idx = NewIndex()
 	for _, pack := range list {
 		for _, blob := range pack.Blobs {
-			idx.store(blob.Type, blob.ID, &pack.ID, blob.Offset, blob.Length)
+			idx.store(blob.Type, blob.ID, pack.ID, blob.Offset, blob.Length)
 		}
 	}
 
diff --git a/repository/index_test.go b/repository/index_test.go
index 4b713eaa7..75d69cd0b 100644
--- a/repository/index_test.go
+++ b/repository/index_test.go
@@ -41,7 +41,7 @@ func TestIndexSerialize(t *testing.T) {
 		for j := 0; j < 20; j++ {
 			id := randomID()
 			length := uint(i*100 + j)
-			idx.Store(pack.Data, id, &packID, pos, length)
+			idx.Store(pack.Data, id, packID, pos, length)
 
 			tests = append(tests, testEntry{
 				id:     id,
@@ -72,7 +72,7 @@ func TestIndexSerialize(t *testing.T) {
 		packID, tpe, offset, length, err := idx.Lookup(testBlob.id)
 		OK(t, err)
 
-		Equals(t, testBlob.pack, *packID)
+		Equals(t, testBlob.pack, packID)
 		Equals(t, testBlob.tpe, tpe)
 		Equals(t, testBlob.offset, offset)
 		Equals(t, testBlob.length, length)
@@ -80,7 +80,7 @@ func TestIndexSerialize(t *testing.T) {
 		packID, tpe, offset, length, err = idx2.Lookup(testBlob.id)
 		OK(t, err)
 
-		Equals(t, testBlob.pack, *packID)
+		Equals(t, testBlob.pack, packID)
 		Equals(t, testBlob.tpe, tpe)
 		Equals(t, testBlob.offset, offset)
 		Equals(t, testBlob.length, length)
@@ -95,7 +95,7 @@ func TestIndexSerialize(t *testing.T) {
 		for j := 0; j < 10; j++ {
 			id := randomID()
 			length := uint(i*100 + j)
-			idx.Store(pack.Data, id, &packID, pos, length)
+			idx.Store(pack.Data, id, packID, pos, length)
 
 			newtests = append(newtests, testEntry{
 				id:     id,
@@ -129,7 +129,7 @@ func TestIndexSerialize(t *testing.T) {
 		packID, tpe, offset, length, err := idx3.Lookup(testBlob.id)
 		OK(t, err)
 
-		Equals(t, testBlob.pack, *packID)
+		Equals(t, testBlob.pack, packID)
 		Equals(t, testBlob.tpe, tpe)
 		Equals(t, testBlob.offset, offset)
 		Equals(t, testBlob.length, length)
@@ -148,7 +148,7 @@ func TestIndexSize(t *testing.T) {
 		for j := 0; j < blobs; j++ {
 			id := randomID()
 			length := uint(i*100 + j)
-			idx.Store(pack.Data, id, &packID, pos, length)
+			idx.Store(pack.Data, id, packID, pos, length)
 
 			pos += length
 		}
@@ -250,7 +250,7 @@ func TestIndexUnserialize(t *testing.T) {
 		packID, tpe, offset, length, err := idx.Lookup(test.id)
 		OK(t, err)
 
-		Equals(t, test.packID, *packID)
+		Equals(t, test.packID, packID)
 		Equals(t, test.tpe, tpe)
 		Equals(t, test.offset, offset)
 		Equals(t, test.length, length)
@@ -267,7 +267,7 @@ func TestIndexUnserializeOld(t *testing.T) {
 		packID, tpe, offset, length, err := idx.Lookup(test.id)
 		OK(t, err)
 
-		Equals(t, test.packID, *packID)
+		Equals(t, test.packID, packID)
 		Equals(t, test.tpe, tpe)
 		Equals(t, test.offset, offset)
 		Equals(t, test.length, length)
@@ -313,7 +313,7 @@ func TestConvertIndex(t *testing.T) {
 				packID, tpe, offset, length, err := oldIndex.Lookup(packedBlob.ID)
 				OK(t, err)
 
-				Assert(t, *packID == packedBlob.PackID,
+				Assert(t, packID == packedBlob.PackID,
 					"Check blob %v: pack ID %v != %v", packedBlob.ID, packID, packedBlob.PackID)
 				Assert(t, tpe == packedBlob.Type,
 					"Check blob %v: Type %v != %v", packedBlob.ID, tpe, packedBlob.Type)
diff --git a/repository/master_index.go b/repository/master_index.go
index 5a61569fa..c6efc20e4 100644
--- a/repository/master_index.go
+++ b/repository/master_index.go
@@ -33,7 +33,7 @@ func NewMasterIndex() *MasterIndex {
 }
 
 // Lookup queries all known Indexes for the ID and returns the first match.
-func (mi *MasterIndex) Lookup(id backend.ID) (packID *backend.ID, tpe pack.BlobType, offset, length uint, err error) {
+func (mi *MasterIndex) Lookup(id backend.ID) (packID backend.ID, tpe pack.BlobType, offset, length uint, err error) {
 	mi.idxMutex.RLock()
 	defer mi.idxMutex.RUnlock()
 
@@ -50,7 +50,7 @@ func (mi *MasterIndex) Lookup(id backend.ID) (packID *backend.ID, tpe pack.BlobT
 	}
 
 	debug.Log("MasterIndex.Lookup", "id %v not found in any index", id.Str())
-	return nil, pack.Data, 0, 0, fmt.Errorf("id %v not found in any index", id)
+	return backend.ID{}, pack.Data, 0, 0, fmt.Errorf("id %v not found in any index", id)
 }
 
 // LookupSize queries all known Indexes for the ID and returns the first match.
diff --git a/repository/repository.go b/repository/repository.go
index 670b71f5d..35d508122 100644
--- a/repository/repository.go
+++ b/repository/repository.go
@@ -269,7 +269,7 @@ func (r *Repository) savePacker(p *pack.Packer) error {
 	// update blobs in the index
 	for _, b := range p.Blobs() {
 		debug.Log("Repo.savePacker", "  updating blob %v to pack %v", b.ID.Str(), sid.Str())
-		r.idx.Current().Store(b.Type, b.ID, &sid, b.Offset, uint(b.Length))
+		r.idx.Current().Store(b.Type, b.ID, sid, b.Offset, uint(b.Length))
 		r.idx.RemoveFromInFlight(b.ID)
 	}