diff --git a/main.go b/main.go
index 1efeedbd2..fd3c533cd 100644
--- a/main.go
+++ b/main.go
@@ -54,7 +54,6 @@ var (
 
 	samplesQueueCapacity = flag.Int("storage.incoming-samples-queue-capacity", 64*1024, "The capacity of the queue of samples to be stored. Note that each slot in the queue takes a whole slice of samples whose size depends on details of the scrape process.")
 
-	chunkType       = flag.Int("storage.local.chunk-type", 1, "Which chunk encoding version to use. Currently supported is 0 (delta encoding) and 1 (double-delta encoding).")
 	numMemoryChunks = flag.Int("storage.local.memory-chunks", 1024*1024, "How many chunks to keep in memory. While the size of a chunk is 1kiB, the total memory usage will be significantly higher than this value * 1kiB. Furthermore, for various reasons, more chunks might have to be kept in memory temporarily.")
 
 	persistenceRetentionPeriod = flag.Duration("storage.local.retention", 15*24*time.Hour, "How long to retain samples in the local storage.")
@@ -123,8 +122,7 @@ func NewPrometheus() *prometheus {
 		PersistenceQueueCapacity:   *persistenceQueueCapacity,
 		CheckpointInterval:         *checkpointInterval,
 		CheckpointDirtySeriesLimit: *checkpointDirtySeriesLimit,
-		ChunkType:                  byte(*chunkType),
-		Dirty:                      *storageDirty,
+		Dirty: *storageDirty,
 	}
 	memStorage, err := local.NewMemorySeriesStorage(o)
 	if err != nil {
diff --git a/storage/local/chunk.go b/storage/local/chunk.go
index 4dbce0523..58110c350 100644
--- a/storage/local/chunk.go
+++ b/storage/local/chunk.go
@@ -15,6 +15,7 @@ package local
 
 import (
 	"container/list"
+	"flag"
 	"fmt"
 	"io"
 	"sync"
@@ -25,6 +26,17 @@ import (
 	"github.com/prometheus/prometheus/storage/metric"
 )
 
+var (
+	defaultChunkEncoding = flag.Int("storage.local.chunk-encoding-version", 1, "Which chunk encoding version to use for newly created chunks. Currently supported is 0 (delta encoding) and 1 (double-delta encoding).")
+)
+
+type chunkEncoding byte
+
+const (
+	delta chunkEncoding = iota
+	doubleDelta
+)
+
 // chunkDesc contains meta-data for a chunk. Many of its methods are
 // goroutine-safe proxies for chunk methods.
 type chunkDesc struct {
@@ -173,13 +185,14 @@ type chunk interface {
 	// any. The first chunk returned might be the same as the original one
 	// or a newly allocated version. In any case, take the returned chunk as
 	// the relevant one and discard the orginal chunk.
-	add(*metric.SamplePair) []chunk
+	add(sample *metric.SamplePair) []chunk
 	clone() chunk
 	firstTime() clientmodel.Timestamp
 	lastTime() clientmodel.Timestamp
 	newIterator() chunkIterator
 	marshal(io.Writer) error
 	unmarshal(io.Reader) error
+	encoding() chunkEncoding
 	// values returns a channel, from which all sample values in the chunk
 	// can be received in order. The channel is closed after the last
 	// one. It is generally not safe to mutate the chunk while the channel
@@ -215,29 +228,22 @@ func transcodeAndAdd(dst chunk, src chunk, s *metric.SamplePair) []chunk {
 		head = newChunks[len(newChunks)-1]
 	}
 	newChunks := head.add(s)
-	body = append(body, newChunks[:len(newChunks)-1]...)
-	head = newChunks[len(newChunks)-1]
-	return append(body, head)
+	return append(body, newChunks...)
 }
 
-func chunkType(c chunk) byte {
-	switch c.(type) {
-	case *deltaEncodedChunk:
-		return 0
-	case *doubleDeltaEncodedChunk:
-		return 1
-	default:
-		panic(fmt.Errorf("unknown chunk type: %T", c))
-	}
+// newChunk creates a new chunk according to the encoding set by the
+// defaultChunkEncoding flag.
+func newChunk() chunk {
+	return newChunkForEncoding(chunkEncoding(*defaultChunkEncoding))
 }
 
-func chunkForType(chunkType byte) chunk {
-	switch chunkType {
-	case 0:
+func newChunkForEncoding(encoding chunkEncoding) chunk {
+	switch encoding {
+	case delta:
 		return newDeltaEncodedChunk(d1, d0, true, chunkLen)
-	case 1:
+	case doubleDelta:
 		return newDoubleDeltaEncodedChunk(d1, d0, true, chunkLen)
 	default:
-		panic(fmt.Errorf("unknown chunk type: %d", chunkType))
+		panic(fmt.Errorf("unknown chunk encoding: %v", encoding))
 	}
 }
diff --git a/storage/local/crashrecovery.go b/storage/local/crashrecovery.go
index b27b5a599..0dc741e40 100644
--- a/storage/local/crashrecovery.go
+++ b/storage/local/crashrecovery.go
@@ -341,7 +341,7 @@ func (p *persistence) cleanUpArchiveIndexes(
 		if err := kv.Value(&m); err != nil {
 			return err
 		}
-		series := newMemorySeries(clientmodel.Metric(m), false, clientmodel.Earliest, p.chunkType)
+		series := newMemorySeries(clientmodel.Metric(m), false, clientmodel.Earliest)
 		cds, err := p.loadChunkDescs(clientmodel.Fingerprint(fp), clientmodel.Now())
 		if err != nil {
 			return err
diff --git a/storage/local/delta.go b/storage/local/delta.go
index 17c374f76..0e4816935 100644
--- a/storage/local/delta.go
+++ b/storage/local/delta.go
@@ -75,37 +75,6 @@ func newDeltaEncodedChunk(tb, vb deltaBytes, isInt bool, length int) *deltaEncod
 	return &c
 }
 
-func (c deltaEncodedChunk) newFollowupChunk() chunk {
-	return newDeltaEncodedChunk(d1, d0, true, cap(c))
-}
-
-// clone implements chunk.
-func (c deltaEncodedChunk) clone() chunk {
-	clone := make(deltaEncodedChunk, len(c), cap(c))
-	copy(clone, c)
-	return &clone
-}
-
-func (c deltaEncodedChunk) timeBytes() deltaBytes {
-	return deltaBytes(c[deltaHeaderTimeBytesOffset])
-}
-
-func (c deltaEncodedChunk) valueBytes() deltaBytes {
-	return deltaBytes(c[deltaHeaderValueBytesOffset])
-}
-
-func (c deltaEncodedChunk) isInt() bool {
-	return c[deltaHeaderIsIntOffset] == 1
-}
-
-func (c deltaEncodedChunk) baseTime() clientmodel.Timestamp {
-	return clientmodel.Timestamp(binary.LittleEndian.Uint64(c[deltaHeaderBaseTimeOffset:]))
-}
-
-func (c deltaEncodedChunk) baseValue() clientmodel.SampleValue {
-	return clientmodel.SampleValue(math.Float64frombits(binary.LittleEndian.Uint64(c[deltaHeaderBaseValueOffset:])))
-}
-
 // add implements chunk.
 func (c deltaEncodedChunk) add(s *metric.SamplePair) []chunk {
 	if c.len() == 0 {
@@ -120,7 +89,7 @@ func (c deltaEncodedChunk) add(s *metric.SamplePair) []chunk {
 	// Do we generally have space for another sample in this chunk? If not,
 	// overflow into a new one.
 	if remainingBytes < sampleSize {
-		overflowChunks := c.newFollowupChunk().add(s)
+		overflowChunks := newChunk().add(s)
 		return []chunk{&c, overflowChunks[0]}
 	}
 
@@ -131,33 +100,38 @@ func (c deltaEncodedChunk) add(s *metric.SamplePair) []chunk {
 	dv := s.Value - baseValue
 	tb := c.timeBytes()
 	vb := c.valueBytes()
+	isInt := c.isInt()
 
 	// If the new sample is incompatible with the current encoding, reencode the
 	// existing chunk data into new chunk(s).
-	//
-	// int->float.
-	if c.isInt() && !isInt64(dv) {
-		return transcodeAndAdd(newDeltaEncodedChunk(tb, d4, false, cap(c)), &c, s)
+
+	ntb, nvb, nInt := tb, vb, isInt
+	if isInt && !isInt64(dv) {
+		// int->float.
+		nvb = d4
+		nInt = false
+	} else if !isInt && vb == d4 && baseValue+clientmodel.SampleValue(float32(dv)) != s.Value {
+		// float32->float64.
+		nvb = d8
+	} else {
+		if tb < d8 {
+			// Maybe more bytes for timestamp.
+			ntb = max(tb, bytesNeededForUnsignedTimestampDelta(dt))
+		}
+		if c.isInt() && vb < d8 {
+			// Maybe more bytes for sample value.
+			nvb = max(vb, bytesNeededForIntegerSampleValueDelta(dv))
+		}
 	}
-	// float32->float64.
-	if !c.isInt() && vb == d4 && baseValue+clientmodel.SampleValue(float32(dv)) != s.Value {
-		return transcodeAndAdd(newDeltaEncodedChunk(tb, d8, false, cap(c)), &c, s)
+	if tb != ntb || vb != nvb || isInt != nInt {
+		if len(c)*2 < cap(c) {
+			return transcodeAndAdd(newDeltaEncodedChunk(ntb, nvb, nInt, cap(c)), &c, s)
+		}
+		// Chunk is already half full. Better create a new one and save the transcoding efforts.
+		overflowChunks := newChunk().add(s)
+		return []chunk{&c, overflowChunks[0]}
 	}
 
-	var ntb, nvb deltaBytes
-	if tb < d8 {
-		// Maybe more bytes for timestamp.
-		ntb = bytesNeededForUnsignedTimestampDelta(dt)
-	}
-	if c.isInt() && vb < d8 {
-		// Maybe more bytes for sample value.
-		nvb = bytesNeededForIntegerSampleValueDelta(dv)
-	}
-	if ntb > tb || nvb > vb {
-		ntb = max(ntb, tb)
-		nvb = max(nvb, vb)
-		return transcodeAndAdd(newDeltaEncodedChunk(ntb, nvb, c.isInt(), cap(c)), &c, s)
-	}
 	offset := len(c)
 	c = c[:offset+sampleSize]
 
@@ -205,15 +179,60 @@ func (c deltaEncodedChunk) add(s *metric.SamplePair) []chunk {
 	return []chunk{&c}
 }
 
-func (c deltaEncodedChunk) sampleSize() int {
-	return int(c.timeBytes() + c.valueBytes())
+// clone implements chunk.
+func (c deltaEncodedChunk) clone() chunk {
+	clone := make(deltaEncodedChunk, len(c), cap(c))
+	copy(clone, c)
+	return &clone
 }
 
-func (c deltaEncodedChunk) len() int {
-	if len(c) < deltaHeaderBytes {
-		return 0
+// firstTime implements chunk.
+func (c deltaEncodedChunk) firstTime() clientmodel.Timestamp {
+	return c.valueAtIndex(0).Timestamp
+}
+
+// lastTime implements chunk.
+func (c deltaEncodedChunk) lastTime() clientmodel.Timestamp {
+	return c.valueAtIndex(c.len() - 1).Timestamp
+}
+
+// newIterator implements chunk.
+func (c *deltaEncodedChunk) newIterator() chunkIterator {
+	return &deltaEncodedChunkIterator{
+		chunk: c,
 	}
-	return (len(c) - deltaHeaderBytes) / c.sampleSize()
+}
+
+// marshal implements chunk.
+func (c deltaEncodedChunk) marshal(w io.Writer) error {
+	if len(c) > math.MaxUint16 {
+		panic("chunk buffer length would overflow a 16 bit uint.")
+	}
+	binary.LittleEndian.PutUint16(c[deltaHeaderBufLenOffset:], uint16(len(c)))
+
+	n, err := w.Write(c[:cap(c)])
+	if err != nil {
+		return err
+	}
+	if n != cap(c) {
+		return fmt.Errorf("wanted to write %d bytes, wrote %d", len(c), n)
+	}
+	return nil
+}
+
+// unmarshal implements chunk.
+func (c *deltaEncodedChunk) unmarshal(r io.Reader) error {
+	*c = (*c)[:cap(*c)]
+	readBytes := 0
+	for readBytes < len(*c) {
+		n, err := r.Read((*c)[readBytes:])
+		if err != nil {
+			return err
+		}
+		readBytes += n
+	}
+	*c = (*c)[:binary.LittleEndian.Uint16((*c)[deltaHeaderBufLenOffset:])]
+	return nil
 }
 
 // values implements chunk.
@@ -229,6 +248,40 @@ func (c deltaEncodedChunk) values() <-chan *metric.SamplePair {
 	return valuesChan
 }
 
+// encoding implements chunk.
+func (c deltaEncodedChunk) encoding() chunkEncoding { return delta }
+
+func (c deltaEncodedChunk) timeBytes() deltaBytes {
+	return deltaBytes(c[deltaHeaderTimeBytesOffset])
+}
+
+func (c deltaEncodedChunk) valueBytes() deltaBytes {
+	return deltaBytes(c[deltaHeaderValueBytesOffset])
+}
+
+func (c deltaEncodedChunk) isInt() bool {
+	return c[deltaHeaderIsIntOffset] == 1
+}
+
+func (c deltaEncodedChunk) baseTime() clientmodel.Timestamp {
+	return clientmodel.Timestamp(binary.LittleEndian.Uint64(c[deltaHeaderBaseTimeOffset:]))
+}
+
+func (c deltaEncodedChunk) baseValue() clientmodel.SampleValue {
+	return clientmodel.SampleValue(math.Float64frombits(binary.LittleEndian.Uint64(c[deltaHeaderBaseValueOffset:])))
+}
+
+func (c deltaEncodedChunk) sampleSize() int {
+	return int(c.timeBytes() + c.valueBytes())
+}
+
+func (c deltaEncodedChunk) len() int {
+	if len(c) < deltaHeaderBytes {
+		return 0
+	}
+	return (len(c) - deltaHeaderBytes) / c.sampleSize()
+}
+
 func (c deltaEncodedChunk) valueAtIndex(idx int) *metric.SamplePair {
 	offset := deltaHeaderBytes + idx*c.sampleSize()
 
@@ -281,61 +334,12 @@ func (c deltaEncodedChunk) valueAtIndex(idx int) *metric.SamplePair {
 	}
 }
 
-// firstTime implements chunk.
-func (c deltaEncodedChunk) firstTime() clientmodel.Timestamp {
-	return c.valueAtIndex(0).Timestamp
-}
-
-// lastTime implements chunk.
-func (c deltaEncodedChunk) lastTime() clientmodel.Timestamp {
-	return c.valueAtIndex(c.len() - 1).Timestamp
-}
-
-// marshal implements chunk.
-func (c deltaEncodedChunk) marshal(w io.Writer) error {
-	if len(c) > math.MaxUint16 {
-		panic("chunk buffer length would overflow a 16 bit uint.")
-	}
-	binary.LittleEndian.PutUint16(c[deltaHeaderBufLenOffset:], uint16(len(c)))
-
-	n, err := w.Write(c[:cap(c)])
-	if err != nil {
-		return err
-	}
-	if n != cap(c) {
-		return fmt.Errorf("wanted to write %d bytes, wrote %d", len(c), n)
-	}
-	return nil
-}
-
-// unmarshal implements chunk.
-func (c *deltaEncodedChunk) unmarshal(r io.Reader) error {
-	*c = (*c)[:cap(*c)]
-	readBytes := 0
-	for readBytes < len(*c) {
-		n, err := r.Read((*c)[readBytes:])
-		if err != nil {
-			return err
-		}
-		readBytes += n
-	}
-	*c = (*c)[:binary.LittleEndian.Uint16((*c)[deltaHeaderBufLenOffset:])]
-	return nil
-}
-
 // deltaEncodedChunkIterator implements chunkIterator.
 type deltaEncodedChunkIterator struct {
 	chunk *deltaEncodedChunk
 	// TODO: add more fields here to keep track of last position.
 }
 
-// newIterator implements chunk.
-func (c *deltaEncodedChunk) newIterator() chunkIterator {
-	return &deltaEncodedChunkIterator{
-		chunk: c,
-	}
-}
-
 // getValueAtTime implements chunkIterator.
 func (it *deltaEncodedChunkIterator) getValueAtTime(t clientmodel.Timestamp) metric.Values {
 	i := sort.Search(it.chunk.len(), func(i int) bool {
diff --git a/storage/local/doubledelta.go b/storage/local/doubledelta.go
index c5ad79817..a1c9ad224 100644
--- a/storage/local/doubledelta.go
+++ b/storage/local/doubledelta.go
@@ -82,10 +82,183 @@ func newDoubleDeltaEncodedChunk(tb, vb deltaBytes, isInt bool, length int) *doub
 	return &c
 }
 
-func (c doubleDeltaEncodedChunk) newFollowupChunk() chunk {
-	return newDoubleDeltaEncodedChunk(d1, d0, true, cap(c))
+// add implements chunk.
+func (c doubleDeltaEncodedChunk) add(s *metric.SamplePair) []chunk {
+	if c.len() == 0 {
+		return c.addFirstSample(s)
+	}
+
+	tb := c.timeBytes()
+	vb := c.valueBytes()
+
+	if c.len() == 1 {
+		return c.addSecondSample(s, tb, vb)
+	}
+
+	remainingBytes := cap(c) - len(c)
+	sampleSize := c.sampleSize()
+
+	// Do we generally have space for another sample in this chunk? If not,
+	// overflow into a new one.
+	if remainingBytes < sampleSize {
+		overflowChunks := newChunk().add(s)
+		return []chunk{&c, overflowChunks[0]}
+	}
+
+	projectedTime := c.baseTime() + clientmodel.Timestamp(c.len())*c.baseTimeDelta()
+	ddt := s.Timestamp - projectedTime
+
+	projectedValue := c.baseValue() + clientmodel.SampleValue(c.len())*c.baseValueDelta()
+	ddv := s.Value - projectedValue
+
+	ntb, nvb, nInt := tb, vb, c.isInt()
+	// If the new sample is incompatible with the current encoding, reencode the
+	// existing chunk data into new chunk(s).
+	if c.isInt() && !isInt64(ddv) {
+		// int->float.
+		nvb = d4
+		nInt = false
+	} else if !c.isInt() && vb == d4 && projectedValue+clientmodel.SampleValue(float32(ddv)) != s.Value {
+		// float32->float64.
+		nvb = d8
+	} else {
+		if tb < d8 {
+			// Maybe more bytes for timestamp.
+			ntb = max(tb, bytesNeededForSignedTimestampDelta(ddt))
+		}
+		if c.isInt() && vb < d8 {
+			// Maybe more bytes for sample value.
+			nvb = max(vb, bytesNeededForIntegerSampleValueDelta(ddv))
+		}
+	}
+	if tb != ntb || vb != nvb || c.isInt() != nInt {
+		if len(c)*2 < cap(c) {
+			return transcodeAndAdd(newDoubleDeltaEncodedChunk(ntb, nvb, nInt, cap(c)), &c, s)
+		}
+		// Chunk is already half full. Better create a new one and save the transcoding efforts.
+		overflowChunks := newChunk().add(s)
+		return []chunk{&c, overflowChunks[0]}
+	}
+
+	offset := len(c)
+	c = c[:offset+sampleSize]
+
+	switch tb {
+	case d1:
+		c[offset] = byte(ddt)
+	case d2:
+		binary.LittleEndian.PutUint16(c[offset:], uint16(ddt))
+	case d4:
+		binary.LittleEndian.PutUint32(c[offset:], uint32(ddt))
+	case d8:
+		// Store the absolute value (no delta) in case of d8.
+		binary.LittleEndian.PutUint64(c[offset:], uint64(s.Timestamp))
+	default:
+		panic("invalid number of bytes for time delta")
+	}
+
+	offset += int(tb)
+
+	if c.isInt() {
+		switch vb {
+		case d0:
+			// No-op. Constant delta is stored as base value.
+		case d1:
+			c[offset] = byte(ddv)
+		case d2:
+			binary.LittleEndian.PutUint16(c[offset:], uint16(ddv))
+		case d4:
+			binary.LittleEndian.PutUint32(c[offset:], uint32(ddv))
+		// d8 must not happen. Those samples are encoded as float64.
+		default:
+			panic("invalid number of bytes for integer delta")
+		}
+	} else {
+		switch vb {
+		case d4:
+			binary.LittleEndian.PutUint32(c[offset:], math.Float32bits(float32(ddv)))
+		case d8:
+			// Store the absolute value (no delta) in case of d8.
+			binary.LittleEndian.PutUint64(c[offset:], math.Float64bits(float64(s.Value)))
+		default:
+			panic("invalid number of bytes for floating point delta")
+		}
+	}
+	return []chunk{&c}
 }
 
+// clone implements chunk.
+func (c doubleDeltaEncodedChunk) clone() chunk {
+	clone := make(doubleDeltaEncodedChunk, len(c), cap(c))
+	copy(clone, c)
+	return &clone
+}
+
+// firstTime implements chunk.
+func (c doubleDeltaEncodedChunk) firstTime() clientmodel.Timestamp {
+	return c.baseTime()
+}
+
+// lastTime implements chunk.
+func (c doubleDeltaEncodedChunk) lastTime() clientmodel.Timestamp {
+	return c.valueAtIndex(c.len() - 1).Timestamp
+}
+
+// newIterator implements chunk.
+func (c *doubleDeltaEncodedChunk) newIterator() chunkIterator {
+	return &doubleDeltaEncodedChunkIterator{
+		chunk: c,
+	}
+}
+
+// marshal implements chunk.
+func (c doubleDeltaEncodedChunk) marshal(w io.Writer) error {
+	if len(c) > math.MaxUint16 {
+		panic("chunk buffer length would overflow a 16 bit uint.")
+	}
+	binary.LittleEndian.PutUint16(c[doubleDeltaHeaderBufLenOffset:], uint16(len(c)))
+
+	n, err := w.Write(c[:cap(c)])
+	if err != nil {
+		return err
+	}
+	if n != cap(c) {
+		return fmt.Errorf("wanted to write %d bytes, wrote %d", len(c), n)
+	}
+	return nil
+}
+
+// unmarshal implements chunk.
+func (c *doubleDeltaEncodedChunk) unmarshal(r io.Reader) error {
+	*c = (*c)[:cap(*c)]
+	readBytes := 0
+	for readBytes < len(*c) {
+		n, err := r.Read((*c)[readBytes:])
+		if err != nil {
+			return err
+		}
+		readBytes += n
+	}
+	*c = (*c)[:binary.LittleEndian.Uint16((*c)[doubleDeltaHeaderBufLenOffset:])]
+	return nil
+}
+
+// values implements chunk.
+func (c doubleDeltaEncodedChunk) values() <-chan *metric.SamplePair {
+	n := c.len()
+	valuesChan := make(chan *metric.SamplePair)
+	go func() {
+		for i := 0; i < n; i++ {
+			valuesChan <- c.valueAtIndex(i)
+		}
+		close(valuesChan)
+	}()
+	return valuesChan
+}
+
+// encoding implements chunk.
+func (c doubleDeltaEncodedChunk) encoding() chunkEncoding { return doubleDelta }
+
 func (c doubleDeltaEncodedChunk) baseTime() clientmodel.Timestamp {
 	return clientmodel.Timestamp(
 		binary.LittleEndian.Uint64(
@@ -148,109 +321,6 @@ func (c doubleDeltaEncodedChunk) isInt() bool {
 	return c[doubleDeltaHeaderIsIntOffset] == 1
 }
 
-// add implements chunk.
-func (c doubleDeltaEncodedChunk) add(s *metric.SamplePair) []chunk {
-	if c.len() == 0 {
-		return c.addFirstSample(s)
-	}
-
-	tb := c.timeBytes()
-	vb := c.valueBytes()
-
-	if c.len() == 1 {
-		return c.addSecondSample(s, tb, vb)
-	}
-
-	remainingBytes := cap(c) - len(c)
-	sampleSize := c.sampleSize()
-
-	// Do we generally have space for another sample in this chunk? If not,
-	// overflow into a new one.
-	if remainingBytes < sampleSize {
-		overflowChunks := c.newFollowupChunk().add(s)
-		return []chunk{&c, overflowChunks[0]}
-	}
-
-	projectedTime := c.baseTime() + clientmodel.Timestamp(c.len())*c.baseTimeDelta()
-	ddt := s.Timestamp - projectedTime
-
-	projectedValue := c.baseValue() + clientmodel.SampleValue(c.len())*c.baseValueDelta()
-	ddv := s.Value - projectedValue
-
-	// If the new sample is incompatible with the current encoding, reencode the
-	// existing chunk data into new chunk(s).
-	//
-	// int->float.
-	if c.isInt() && !isInt64(ddv) {
-		return transcodeAndAdd(newDoubleDeltaEncodedChunk(tb, d4, false, cap(c)), &c, s)
-	}
-	// float32->float64.
-	if !c.isInt() && vb == d4 && projectedValue+clientmodel.SampleValue(float32(ddv)) != s.Value {
-		return transcodeAndAdd(newDoubleDeltaEncodedChunk(tb, d8, false, cap(c)), &c, s)
-	}
-
-	var ntb, nvb deltaBytes
-	if tb < d8 {
-		// Maybe more bytes for timestamp.
-		ntb = bytesNeededForSignedTimestampDelta(ddt)
-	}
-	if c.isInt() && vb < d8 {
-		// Maybe more bytes for sample value.
-		nvb = bytesNeededForIntegerSampleValueDelta(ddv)
-	}
-	if ntb > tb || nvb > vb {
-		ntb = max(ntb, tb)
-		nvb = max(nvb, vb)
-		return transcodeAndAdd(newDoubleDeltaEncodedChunk(ntb, nvb, c.isInt(), cap(c)), &c, s)
-	}
-
-	offset := len(c)
-	c = c[:offset+sampleSize]
-
-	switch tb {
-	case d1:
-		c[offset] = byte(ddt)
-	case d2:
-		binary.LittleEndian.PutUint16(c[offset:], uint16(ddt))
-	case d4:
-		binary.LittleEndian.PutUint32(c[offset:], uint32(ddt))
-	case d8:
-		// Store the absolute value (no delta) in case of d8.
-		binary.LittleEndian.PutUint64(c[offset:], uint64(s.Timestamp))
-	default:
-		panic("invalid number of bytes for time delta")
-	}
-
-	offset += int(tb)
-
-	if c.isInt() {
-		switch vb {
-		case d0:
-			// No-op. Constant delta is stored as base value.
-		case d1:
-			c[offset] = byte(ddv)
-		case d2:
-			binary.LittleEndian.PutUint16(c[offset:], uint16(ddv))
-		case d4:
-			binary.LittleEndian.PutUint32(c[offset:], uint32(ddv))
-		// d8 must not happen. Those samples are encoded as float64.
-		default:
-			panic("invalid number of bytes for integer delta")
-		}
-	} else {
-		switch vb {
-		case d4:
-			binary.LittleEndian.PutUint32(c[offset:], math.Float32bits(float32(ddv)))
-		case d8:
-			// Store the absolute value (no delta) in case of d8.
-			binary.LittleEndian.PutUint64(c[offset:], math.Float64bits(float64(s.Value)))
-		default:
-			panic("invalid number of bytes for floating point delta")
-		}
-	}
-	return []chunk{&c}
-}
-
 // addFirstSample is a helper method only used by c.add(). It adds timestamp and
 // value as base time and value.
 func (c doubleDeltaEncodedChunk) addFirstSample(s *metric.SamplePair) []chunk {
@@ -315,26 +385,6 @@ func (c doubleDeltaEncodedChunk) addSecondSample(s *metric.SamplePair, tb, vb de
 	return []chunk{&c}
 }
 
-// clone implements chunk.
-func (c doubleDeltaEncodedChunk) clone() chunk {
-	clone := make(doubleDeltaEncodedChunk, len(c), cap(c))
-	copy(clone, c)
-	return &clone
-}
-
-// values implements chunk.
-func (c doubleDeltaEncodedChunk) values() <-chan *metric.SamplePair {
-	n := c.len()
-	valuesChan := make(chan *metric.SamplePair)
-	go func() {
-		for i := 0; i < n; i++ {
-			valuesChan <- c.valueAtIndex(i)
-		}
-		close(valuesChan)
-	}()
-	return valuesChan
-}
-
 func (c doubleDeltaEncodedChunk) valueAtIndex(idx int) *metric.SamplePair {
 	if idx == 0 {
 		return &metric.SamplePair{
@@ -424,61 +474,12 @@ func (c doubleDeltaEncodedChunk) valueAtIndex(idx int) *metric.SamplePair {
 	}
 }
 
-// firstTime implements chunk.
-func (c doubleDeltaEncodedChunk) firstTime() clientmodel.Timestamp {
-	return c.baseTime()
-}
-
-// lastTime implements chunk.
-func (c doubleDeltaEncodedChunk) lastTime() clientmodel.Timestamp {
-	return c.valueAtIndex(c.len() - 1).Timestamp
-}
-
-// marshal implements chunk.
-func (c doubleDeltaEncodedChunk) marshal(w io.Writer) error {
-	if len(c) > math.MaxUint16 {
-		panic("chunk buffer length would overflow a 16 bit uint.")
-	}
-	binary.LittleEndian.PutUint16(c[doubleDeltaHeaderBufLenOffset:], uint16(len(c)))
-
-	n, err := w.Write(c[:cap(c)])
-	if err != nil {
-		return err
-	}
-	if n != cap(c) {
-		return fmt.Errorf("wanted to write %d bytes, wrote %d", len(c), n)
-	}
-	return nil
-}
-
-// unmarshal implements chunk.
-func (c *doubleDeltaEncodedChunk) unmarshal(r io.Reader) error {
-	*c = (*c)[:cap(*c)]
-	readBytes := 0
-	for readBytes < len(*c) {
-		n, err := r.Read((*c)[readBytes:])
-		if err != nil {
-			return err
-		}
-		readBytes += n
-	}
-	*c = (*c)[:binary.LittleEndian.Uint16((*c)[doubleDeltaHeaderBufLenOffset:])]
-	return nil
-}
-
 // doubleDeltaEncodedChunkIterator implements chunkIterator.
 type doubleDeltaEncodedChunkIterator struct {
 	chunk *doubleDeltaEncodedChunk
 	// TODO(beorn7): add more fields here to keep track of last position.
 }
 
-// newIterator implements chunk.
-func (c *doubleDeltaEncodedChunk) newIterator() chunkIterator {
-	return &doubleDeltaEncodedChunkIterator{
-		chunk: c,
-	}
-}
-
 // getValueAtTime implements chunkIterator.
 func (it *doubleDeltaEncodedChunkIterator) getValueAtTime(t clientmodel.Timestamp) metric.Values {
 	// TODO(beorn7): Implement in a more efficient way making use of the
diff --git a/storage/local/persistence.go b/storage/local/persistence.go
index 590a6256a..74a02da6c 100644
--- a/storage/local/persistence.go
+++ b/storage/local/persistence.go
@@ -95,8 +95,7 @@ type indexingOp struct {
 // dropChunks, loadChunks, and loadChunkDescs can be called concurrently with
 // each other if each call refers to a different fingerprint.
 type persistence struct {
-	basePath  string
-	chunkType byte
+	basePath string
 
 	archivedFingerprintToMetrics   *index.FingerprintMetricIndex
 	archivedFingerprintToTimeRange *index.FingerprintTimeRangeIndex
@@ -121,7 +120,7 @@ type persistence struct {
 }
 
 // newPersistence returns a newly allocated persistence backed by local disk storage, ready to use.
-func newPersistence(basePath string, chunkType byte, dirty bool) (*persistence, error) {
+func newPersistence(basePath string, dirty bool) (*persistence, error) {
 	dirtyPath := filepath.Join(basePath, dirtyFileName)
 	versionPath := filepath.Join(basePath, versionFileName)
 
@@ -178,8 +177,7 @@ func newPersistence(basePath string, chunkType byte, dirty bool) (*persistence,
 	}
 
 	p := &persistence{
-		basePath:  basePath,
-		chunkType: chunkType,
+		basePath: basePath,
 
 		archivedFingerprintToMetrics:   archivedFingerprintToMetrics,
 		archivedFingerprintToTimeRange: archivedFingerprintToTimeRange,
@@ -396,7 +394,7 @@ func (p *persistence) loadChunks(fp clientmodel.Fingerprint, indexes []int, inde
 		if err != nil {
 			return nil, err
 		}
-		chunk := chunkForType(typeBuf[0])
+		chunk := newChunkForEncoding(chunkEncoding(typeBuf[0]))
 		chunk.unmarshal(f)
 		chunks = append(chunks, chunk)
 	}
@@ -590,7 +588,7 @@ func (p *persistence) checkpointSeriesMapAndHeads(fingerprintToSeries *seriesMap
 					}
 				} else {
 					// This is the non-persisted head chunk. Fully marshal it.
-					if err = w.WriteByte(chunkType(chunkDesc.chunk)); err != nil {
+					if err = w.WriteByte(byte(chunkDesc.chunk.encoding())); err != nil {
 						return
 					}
 					if err = chunkDesc.chunk.marshal(w); err != nil {
@@ -742,13 +740,13 @@ func (p *persistence) loadSeriesMapAndHeads() (sm *seriesMap, err error) {
 				}
 			} else {
 				// Non-persisted head chunk.
-				chunkType, err := r.ReadByte()
+				encoding, err := r.ReadByte()
 				if err != nil {
 					glog.Warning("Could not decode chunk type:", err)
 					p.dirty = true
 					return sm, nil
 				}
-				chunk := chunkForType(chunkType)
+				chunk := newChunkForEncoding(chunkEncoding(encoding))
 				if err := chunk.unmarshal(r); err != nil {
 					glog.Warning("Could not decode chunk type:", err)
 					p.dirty = true
@@ -771,7 +769,6 @@ func (p *persistence) loadSeriesMapAndHeads() (sm *seriesMap, err error) {
 			chunkDescsOffset:   int(chunkDescsOffset),
 			savedFirstTime:     clientmodel.Timestamp(savedFirstTime),
 			headChunkPersisted: headChunkPersisted,
-			chunkType:          p.chunkType,
 		}
 	}
 	return sm, nil
@@ -1096,7 +1093,7 @@ func (p *persistence) openChunkFileForReading(fp clientmodel.Fingerprint) (*os.F
 
 func writeChunkHeader(w io.Writer, c chunk) error {
 	header := make([]byte, chunkHeaderLen)
-	header[chunkHeaderTypeOffset] = chunkType(c)
+	header[chunkHeaderTypeOffset] = byte(c.encoding())
 	binary.LittleEndian.PutUint64(header[chunkHeaderFirstTimeOffset:], uint64(c.firstTime()))
 	binary.LittleEndian.PutUint64(header[chunkHeaderLastTimeOffset:], uint64(c.lastTime()))
 	_, err := w.Write(header)
diff --git a/storage/local/persistence_test.go b/storage/local/persistence_test.go
index a33c5fba4..382eb034a 100644
--- a/storage/local/persistence_test.go
+++ b/storage/local/persistence_test.go
@@ -31,9 +31,10 @@ var (
 	m3 = clientmodel.Metric{"label": "value3"}
 )
 
-func newTestPersistence(t *testing.T, chunkType byte) (*persistence, test.Closer) {
+func newTestPersistence(t *testing.T, encoding chunkEncoding) (*persistence, test.Closer) {
+	*defaultChunkEncoding = int(encoding)
 	dir := test.NewTemporaryDirectory("test_persistence", t)
-	p, err := newPersistence(dir.Path(), chunkType, false)
+	p, err := newPersistence(dir.Path(), false)
 	if err != nil {
 		dir.Close()
 		t.Fatal(err)
@@ -44,7 +45,7 @@ func newTestPersistence(t *testing.T, chunkType byte) (*persistence, test.Closer
 	})
 }
 
-func buildTestChunks(chunkType byte) map[clientmodel.Fingerprint][]chunk {
+func buildTestChunks(encoding chunkEncoding) map[clientmodel.Fingerprint][]chunk {
 	fps := clientmodel.Fingerprints{
 		m1.Fingerprint(),
 		m2.Fingerprint(),
@@ -55,7 +56,7 @@ func buildTestChunks(chunkType byte) map[clientmodel.Fingerprint][]chunk {
 	for _, fp := range fps {
 		fpToChunks[fp] = make([]chunk, 0, 10)
 		for i := 0; i < 10; i++ {
-			fpToChunks[fp] = append(fpToChunks[fp], chunkForType(chunkType).add(&metric.SamplePair{
+			fpToChunks[fp] = append(fpToChunks[fp], newChunkForEncoding(encoding).add(&metric.SamplePair{
 				Timestamp: clientmodel.Timestamp(i),
 				Value:     clientmodel.SampleValue(fp),
 			})[0])
@@ -75,11 +76,11 @@ func chunksEqual(c1, c2 chunk) bool {
 	return true
 }
 
-func testPersistLoadDropChunks(t *testing.T, chunkType byte) {
-	p, closer := newTestPersistence(t, chunkType)
+func testPersistLoadDropChunks(t *testing.T, encoding chunkEncoding) {
+	p, closer := newTestPersistence(t, encoding)
 	defer closer.Close()
 
-	fpToChunks := buildTestChunks(chunkType)
+	fpToChunks := buildTestChunks(encoding)
 
 	for fp, chunks := range fpToChunks {
 		for i, c := range chunks {
@@ -191,15 +192,15 @@ func TestPersistLoadDropChunksType1(t *testing.T) {
 	testPersistLoadDropChunks(t, 1)
 }
 
-func testCheckpointAndLoadSeriesMapAndHeads(t *testing.T, chunkType byte) {
-	p, closer := newTestPersistence(t, chunkType)
+func testCheckpointAndLoadSeriesMapAndHeads(t *testing.T, encoding chunkEncoding) {
+	p, closer := newTestPersistence(t, encoding)
 	defer closer.Close()
 
 	fpLocker := newFingerprintLocker(10)
 	sm := newSeriesMap()
-	s1 := newMemorySeries(m1, true, 0, chunkType)
-	s2 := newMemorySeries(m2, false, 0, chunkType)
-	s3 := newMemorySeries(m3, false, 0, chunkType)
+	s1 := newMemorySeries(m1, true, 0)
+	s2 := newMemorySeries(m2, false, 0)
+	s3 := newMemorySeries(m3, false, 0)
 	s1.add(m1.Fingerprint(), &metric.SamplePair{Timestamp: 1, Value: 3.14})
 	s3.add(m1.Fingerprint(), &metric.SamplePair{Timestamp: 2, Value: 2.7})
 	s3.headChunkPersisted = true
@@ -260,8 +261,8 @@ func TestCheckpointAndLoadSeriesMapAndHeadsChunkType1(t *testing.T) {
 	testCheckpointAndLoadSeriesMapAndHeads(t, 1)
 }
 
-func testGetFingerprintsModifiedBefore(t *testing.T, chunkType byte) {
-	p, closer := newTestPersistence(t, chunkType)
+func testGetFingerprintsModifiedBefore(t *testing.T, encoding chunkEncoding) {
+	p, closer := newTestPersistence(t, encoding)
 	defer closer.Close()
 
 	m1 := clientmodel.Metric{"n1": "v1"}
@@ -338,8 +339,8 @@ func TestGetFingerprintsModifiedBeforeChunkType1(t *testing.T) {
 	testGetFingerprintsModifiedBefore(t, 1)
 }
 
-func testDropArchivedMetric(t *testing.T, chunkType byte) {
-	p, closer := newTestPersistence(t, chunkType)
+func testDropArchivedMetric(t *testing.T, encoding chunkEncoding) {
+	p, closer := newTestPersistence(t, encoding)
 	defer closer.Close()
 
 	m1 := clientmodel.Metric{"n1": "v1"}
@@ -420,7 +421,7 @@ type incrementalBatch struct {
 	expectedLpToFps index.LabelPairFingerprintsMapping
 }
 
-func testIndexing(t *testing.T, chunkType byte) {
+func testIndexing(t *testing.T, encoding chunkEncoding) {
 	batches := []incrementalBatch{
 		{
 			fpToMetric: index.FingerprintMetricMapping{
@@ -556,7 +557,7 @@ func testIndexing(t *testing.T, chunkType byte) {
 		},
 	}
 
-	p, closer := newTestPersistence(t, chunkType)
+	p, closer := newTestPersistence(t, encoding)
 	defer closer.Close()
 
 	indexedFpsToMetrics := index.FingerprintMetricMapping{}
diff --git a/storage/local/series.go b/storage/local/series.go
index c50bb9412..7a4ace7fc 100644
--- a/storage/local/series.go
+++ b/storage/local/series.go
@@ -158,8 +158,6 @@ type memorySeries struct {
 	// a non-persisted head chunk has to be cloned before more samples are
 	// appended.
 	headChunkUsedByIterator bool
-	// Which type of chunk to create if a new chunk is needed.
-	chunkType byte
 }
 
 // newMemorySeries returns a pointer to a newly allocated memorySeries for the
@@ -167,13 +165,11 @@ type memorySeries struct {
 // or (if false) a series for a metric being unarchived, i.e. a series that
 // existed before but has been evicted from memory. If reallyNew is false,
 // firstTime is ignored (and set to the lowest possible timestamp instead - it
-// will be set properly upon the first eviction of chunkDescs). chunkType is the
-// type of chunks newly created by this memorySeries.
+// will be set properly upon the first eviction of chunkDescs).
 func newMemorySeries(
 	m clientmodel.Metric,
 	reallyNew bool,
 	firstTime clientmodel.Timestamp,
-	chunkType byte,
 ) *memorySeries {
 	if reallyNew {
 		firstTime = clientmodel.Earliest
@@ -182,7 +178,6 @@ func newMemorySeries(
 		metric:             m,
 		headChunkPersisted: !reallyNew,
 		savedFirstTime:     firstTime,
-		chunkType:          chunkType,
 	}
 	if !reallyNew {
 		s.chunkDescsOffset = -1
@@ -195,7 +190,7 @@ func newMemorySeries(
 // The caller must have locked the fingerprint of the series.
 func (s *memorySeries) add(fp clientmodel.Fingerprint, v *metric.SamplePair) []*chunkDesc {
 	if len(s.chunkDescs) == 0 || s.headChunkPersisted {
-		newHead := newChunkDesc(chunkForType(s.chunkType))
+		newHead := newChunkDesc(newChunk())
 		s.chunkDescs = append(s.chunkDescs, newHead)
 		s.headChunkPersisted = false
 	} else if s.headChunkUsedByIterator && s.head().getRefCount() > 1 {
diff --git a/storage/local/storage.go b/storage/local/storage.go
index c655e5311..d71117050 100644
--- a/storage/local/storage.go
+++ b/storage/local/storage.go
@@ -16,7 +16,6 @@ package local
 
 import (
 	"container/list"
-	"fmt"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -72,7 +71,6 @@ type memorySeriesStorage struct {
 	dropAfter                  time.Duration
 	checkpointInterval         time.Duration
 	checkpointDirtySeriesLimit int
-	chunkType                  byte
 
 	appendQueue         chan *clientmodel.Sample
 	appendLastTimestamp clientmodel.Timestamp // The timestamp of the last sample sent to the append queue.
@@ -110,17 +108,13 @@ type MemorySeriesStorageOptions struct {
 	PersistenceQueueCapacity   int           // Capacity of queue for chunks to be persisted.
 	CheckpointInterval         time.Duration // How often to checkpoint the series map and head chunks.
 	CheckpointDirtySeriesLimit int           // How many dirty series will trigger an early checkpoint.
-	ChunkType                  byte          // Chunk type for newly created chunks.
 	Dirty                      bool          // Force the storage to consider itself dirty on startup.
 }
 
 // NewMemorySeriesStorage returns a newly allocated Storage. Storage.Serve still
 // has to be called to start the storage.
 func NewMemorySeriesStorage(o *MemorySeriesStorageOptions) (Storage, error) {
-	if o.ChunkType > 1 {
-		return nil, fmt.Errorf("unsupported chunk type %d", o.ChunkType)
-	}
-	p, err := newPersistence(o.PersistenceStoragePath, o.ChunkType, o.Dirty)
+	p, err := newPersistence(o.PersistenceStoragePath, o.Dirty)
 	if err != nil {
 		return nil, err
 	}
@@ -148,7 +142,6 @@ func NewMemorySeriesStorage(o *MemorySeriesStorageOptions) (Storage, error) {
 		dropAfter:                  o.PersistenceRetentionPeriod,
 		checkpointInterval:         o.CheckpointInterval,
 		checkpointDirtySeriesLimit: o.CheckpointDirtySeriesLimit,
-		chunkType:                  o.ChunkType,
 
 		appendLastTimestamp: clientmodel.Earliest,
 		appendQueue:         make(chan *clientmodel.Sample, appendQueueCap),
@@ -458,7 +451,7 @@ func (s *memorySeriesStorage) getOrCreateSeries(fp clientmodel.Fingerprint, m cl
 			s.persistence.indexMetric(fp, m)
 			s.seriesOps.WithLabelValues(create).Inc()
 		}
-		series = newMemorySeries(m, !unarchived, firstTime, s.chunkType)
+		series = newMemorySeries(m, !unarchived, firstTime)
 		s.fpToSeries.put(fp, series)
 		s.numSeries.Inc()
 	}
diff --git a/storage/local/storage_test.go b/storage/local/storage_test.go
index d045dee77..7e773dcc0 100644
--- a/storage/local/storage_test.go
+++ b/storage/local/storage_test.go
@@ -181,7 +181,7 @@ func TestLoop(t *testing.T) {
 	}
 }
 
-func testChunk(t *testing.T, chunkType byte) {
+func testChunk(t *testing.T, encoding chunkEncoding) {
 	samples := make(clientmodel.Samples, 500000)
 	for i := range samples {
 		samples[i] = &clientmodel.Sample{
@@ -189,7 +189,7 @@ func testChunk(t *testing.T, chunkType byte) {
 			Value:     clientmodel.SampleValue(float64(i) * 0.2),
 		}
 	}
-	s, closer := NewTestStorage(t, chunkType)
+	s, closer := NewTestStorage(t, encoding)
 	defer closer.Close()
 
 	s.AppendSamples(samples)
@@ -229,7 +229,7 @@ func TestChunkType1(t *testing.T) {
 	testChunk(t, 1)
 }
 
-func testGetValueAtTime(t *testing.T, chunkType byte) {
+func testGetValueAtTime(t *testing.T, encoding chunkEncoding) {
 	samples := make(clientmodel.Samples, 1000)
 	for i := range samples {
 		samples[i] = &clientmodel.Sample{
@@ -237,7 +237,7 @@ func testGetValueAtTime(t *testing.T, chunkType byte) {
 			Value:     clientmodel.SampleValue(float64(i) * 0.2),
 		}
 	}
-	s, closer := NewTestStorage(t, chunkType)
+	s, closer := NewTestStorage(t, encoding)
 	defer closer.Close()
 
 	s.AppendSamples(samples)
@@ -320,7 +320,7 @@ func TestGetValueAtTimeChunkType1(t *testing.T) {
 	testGetValueAtTime(t, 1)
 }
 
-func testGetRangeValues(t *testing.T, chunkType byte) {
+func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
 	samples := make(clientmodel.Samples, 1000)
 	for i := range samples {
 		samples[i] = &clientmodel.Sample{
@@ -328,7 +328,7 @@ func testGetRangeValues(t *testing.T, chunkType byte) {
 			Value:     clientmodel.SampleValue(float64(i) * 0.2),
 		}
 	}
-	s, closer := NewTestStorage(t, chunkType)
+	s, closer := NewTestStorage(t, encoding)
 	defer closer.Close()
 
 	s.AppendSamples(samples)
@@ -470,7 +470,7 @@ func TestGetRangeValuesChunkType1(t *testing.T) {
 	testGetRangeValues(t, 1)
 }
 
-func testEvictAndPurgeSeries(t *testing.T, chunkType byte) {
+func testEvictAndPurgeSeries(t *testing.T, encoding chunkEncoding) {
 	samples := make(clientmodel.Samples, 1000)
 	for i := range samples {
 		samples[i] = &clientmodel.Sample{
@@ -478,7 +478,7 @@ func testEvictAndPurgeSeries(t *testing.T, chunkType byte) {
 			Value:     clientmodel.SampleValue(float64(i * i)),
 		}
 	}
-	s, closer := NewTestStorage(t, chunkType)
+	s, closer := NewTestStorage(t, encoding)
 	defer closer.Close()
 
 	ms := s.(*memorySeriesStorage) // Going to test the internal maintain.*Series methods.
@@ -576,7 +576,7 @@ func TestEvictAndPurgeSeriesChunkType1(t *testing.T) {
 	testEvictAndPurgeSeries(t, 1)
 }
 
-func benchmarkAppend(b *testing.B, chunkType byte) {
+func benchmarkAppend(b *testing.B, encoding chunkEncoding) {
 	samples := make(clientmodel.Samples, b.N)
 	for i := range samples {
 		samples[i] = &clientmodel.Sample{
@@ -590,7 +590,7 @@ func benchmarkAppend(b *testing.B, chunkType byte) {
 		}
 	}
 	b.ResetTimer()
-	s, closer := NewTestStorage(b, chunkType)
+	s, closer := NewTestStorage(b, encoding)
 	defer closer.Close()
 
 	s.AppendSamples(samples)
@@ -606,14 +606,14 @@ func BenchmarkAppendType1(b *testing.B) {
 
 // Append a large number of random samples and then check if we can get them out
 // of the storage alright.
-func testFuzz(t *testing.T, chunkType byte) {
+func testFuzz(t *testing.T, encoding chunkEncoding) {
 	if testing.Short() {
 		t.Skip("Skipping test in short mode.")
 	}
 
 	check := func(seed int64) bool {
 		rand.Seed(seed)
-		s, c := NewTestStorage(t, chunkType)
+		s, c := NewTestStorage(t, encoding)
 		defer c.Close()
 
 		samples := createRandomSamples("test_fuzz", 1000)
@@ -645,7 +645,8 @@ func TestFuzzChunkType1(t *testing.T) {
 // make things even slower):
 //
 // go test -race -cpu 8 -test=short -bench BenchmarkFuzzChunkType
-func benchmarkFuzz(b *testing.B, chunkType byte) {
+func benchmarkFuzz(b *testing.B, encoding chunkEncoding) {
+	*defaultChunkEncoding = int(encoding)
 	const samplesPerRun = 100000
 	rand.Seed(42)
 	directory := test.NewTemporaryDirectory("test_storage", b)
@@ -655,7 +656,6 @@ func benchmarkFuzz(b *testing.B, chunkType byte) {
 		PersistenceRetentionPeriod: time.Hour,
 		PersistenceStoragePath:     directory.Path(),
 		CheckpointInterval:         time.Second,
-		ChunkType:                  chunkType,
 	}
 	s, err := NewMemorySeriesStorage(o)
 	if err != nil {
diff --git a/storage/local/test_helpers.go b/storage/local/test_helpers.go
index 319398497..2fc78d429 100644
--- a/storage/local/test_helpers.go
+++ b/storage/local/test_helpers.go
@@ -37,14 +37,14 @@ func (t *testStorageCloser) Close() {
 // NewTestStorage creates a storage instance backed by files in a temporary
 // directory. The returned storage is already in serving state. Upon closing the
 // returned test.Closer, the temporary directory is cleaned up.
-func NewTestStorage(t test.T, chunkType byte) (Storage, test.Closer) {
+func NewTestStorage(t test.T, encoding chunkEncoding) (Storage, test.Closer) {
+	*defaultChunkEncoding = int(encoding)
 	directory := test.NewTemporaryDirectory("test_storage", t)
 	o := &MemorySeriesStorageOptions{
 		MemoryChunks:               1000000,
 		PersistenceRetentionPeriod: 24 * time.Hour * 365 * 100, // Enough to never trigger purging.
 		PersistenceStoragePath:     directory.Path(),
 		CheckpointInterval:         time.Hour,
-		ChunkType:                  chunkType,
 	}
 	storage, err := NewMemorySeriesStorage(o)
 	if err != nil {