diff --git a/head.go b/head.go
index 9319980044..01110f1a29 100644
--- a/head.go
+++ b/head.go
@@ -269,13 +269,19 @@ func (h *HeadBlock) persist(p string) (int64, error) {
 	}
 
 	iw := newIndexWriter(xf)
-	sw := newSeriesWriter(sf, iw, h.stats.MinTime)
+	sw := newSeriesWriter(sf, iw)
 
 	defer sw.Close()
 	defer iw.Close()
 
 	for ref, cd := range h.descs {
-		if err := sw.WriteSeries(uint32(ref), cd.lset, []*chunkDesc{cd}); err != nil {
+		if err := sw.WriteSeries(uint32(ref), cd.lset, []ChunkMeta{
+			{
+				MinTime: cd.firsTimestamp,
+				MaxTime: cd.lastTimestamp,
+				Chunk:   cd.chunk,
+			},
+		}); err != nil {
 			return 0, err
 		}
 	}
@@ -299,6 +305,14 @@ func (h *HeadBlock) persist(p string) (int64, error) {
 			return 0, err
 		}
 	}
+	// Write a postings list containing all series.
+	all := make([]uint32, len(h.descs))
+	for i := range all {
+		all[i] = uint32(i)
+	}
+	if err := iw.WritePostings("", "", newListPostings(all)); err != nil {
+		return 0, err
+	}
 
 	// Everything written successfully, we can remove the WAL.
 	if err := h.wal.Close(); err != nil {
diff --git a/writer.go b/writer.go
index ff2154533e..e3f24f370c 100644
--- a/writer.go
+++ b/writer.go
@@ -10,6 +10,7 @@ import (
 	"strings"
 
 	"github.com/bradfitz/slice"
+	"github.com/fabxc/tsdb/chunks"
 	"github.com/fabxc/tsdb/labels"
 	"github.com/pkg/errors"
 )
@@ -27,7 +28,7 @@ type SeriesWriter interface {
 	// WriteSeries writes the time series data chunks for a single series.
 	// The reference is used to resolve the correct series in the written index.
 	// It only has to be valid for the duration of the write.
-	WriteSeries(ref uint32, l labels.Labels, cds []*chunkDesc) error
+	WriteSeries(ref uint32, l labels.Labels, chunks []ChunkMeta) error
 
 	// Size returns the size of the data written so far.
 	Size() int64
@@ -44,16 +45,14 @@ type seriesWriter struct {
 	n int64
 	c int
 
-	baseTimestamp int64
-	index         IndexWriter
+	index IndexWriter
 }
 
-func newSeriesWriter(w io.Writer, index IndexWriter, base int64) *seriesWriter {
+func newSeriesWriter(w io.Writer, index IndexWriter) *seriesWriter {
 	return &seriesWriter{
-		w:             w,
-		n:             0,
-		index:         index,
-		baseTimestamp: base,
+		w:     w,
+		n:     0,
+		index: index,
 	}
 }
 
@@ -72,7 +71,7 @@ func (w *seriesWriter) writeMeta() error {
 	return w.write(w.w, b[:])
 }
 
-func (w *seriesWriter) WriteSeries(ref uint32, lset labels.Labels, chks []*chunkDesc) error {
+func (w *seriesWriter) WriteSeries(ref uint32, lset labels.Labels, chks []ChunkMeta) error {
 	// Initialize with meta data.
 	if w.n == 0 {
 		if err := w.writeMeta(); err != nil {
@@ -96,25 +95,23 @@ func (w *seriesWriter) WriteSeries(ref uint32, lset labels.Labels, chks []*chunk
 		return err
 	}
 
-	metas := make([]ChunkMeta, 0, len(chks))
+	for i := range chks {
+		chk := &chks[i]
 
-	for _, cd := range chks {
-		metas = append(metas, ChunkMeta{
-			MinTime: cd.firsTimestamp,
-			MaxTime: cd.lastTimestamp,
-			Ref:     uint32(w.n),
-		})
-		n = binary.PutUvarint(b[:], uint64(len(cd.chunk.Bytes())))
+		chk.Ref = uint32(w.n)
+
+		n = binary.PutUvarint(b[:], uint64(len(chk.Chunk.Bytes())))
 
 		if err := w.write(wr, b[:n]); err != nil {
 			return err
 		}
-		if err := w.write(wr, []byte{byte(cd.chunk.Encoding())}); err != nil {
+		if err := w.write(wr, []byte{byte(chk.Chunk.Encoding())}); err != nil {
 			return err
 		}
-		if err := w.write(wr, cd.chunk.Bytes()); err != nil {
+		if err := w.write(wr, chk.Chunk.Bytes()); err != nil {
 			return err
 		}
+		chk.Chunk = nil
 	}
 
 	if err := w.write(w.w, h.Sum(nil)); err != nil {
@@ -122,7 +119,7 @@ func (w *seriesWriter) WriteSeries(ref uint32, lset labels.Labels, chks []*chunk
 	}
 
 	if w.index != nil {
-		w.index.AddSeries(ref, lset, metas...)
+		w.index.AddSeries(ref, lset, chks...)
 	}
 	return nil
 }
@@ -144,10 +141,15 @@ func (w *seriesWriter) Close() error {
 	return nil
 }
 
+// ChunkMeta holds information about a chunk of data.
 type ChunkMeta struct {
-	Ref     uint32
-	MinTime int64
-	MaxTime int64
+	// Ref and Chunk hold either a reference that can be used to retrieve
+	// chunk data or the data itself.
+	// Generally, only one of them is set.
+	Ref   uint32
+	Chunk chunks.Chunk
+
+	MinTime, MaxTime int64 // time range the data covers
 }
 
 // IndexWriter serialized the index for a block of series data.