diff --git a/markets/dagstore/piecereader.go b/markets/dagstore/piecereader.go
index f9ba881f5..14a027bd1 100644
--- a/markets/dagstore/piecereader.go
+++ b/markets/dagstore/piecereader.go
@@ -1,21 +1,23 @@
 package dagstore
 
 import (
+	"bufio"
 	"context"
-	"github.com/filecoin-project/lotus/metrics"
-	"go.opencensus.io/stats"
 	"io"
 
 	"github.com/ipfs/go-cid"
+	"go.opencensus.io/stats"
 	"golang.org/x/xerrors"
 
 	"github.com/filecoin-project/dagstore/mount"
 	"github.com/filecoin-project/go-state-types/abi"
+	"github.com/filecoin-project/lotus/metrics"
 )
 
 // For small read skips, it's faster to "burn" some bytes than to setup new sector reader.
 // Assuming 1ms stream seek latency, and 1G/s stream rate, we're willing to discard up to 1 MiB.
 var MaxPieceReaderBurnBytes int64 = 1 << 20 // 1M
+var ReadBuf = 128 * (127 * 8)               // unpadded(128k)
 
 type pieceReader struct {
 	ctx      context.Context
@@ -27,6 +29,7 @@ type pieceReader struct {
 	seqAt  int64 // next byte to be read by io.Reader
 
 	r   io.ReadCloser
+	br  *bufio.Reader
 	rAt int64
 }
 
@@ -38,6 +41,7 @@ func (p *pieceReader) init() (_ *pieceReader, err error) {
 	if err != nil {
 		return nil, err
 	}
+	p.br = bufio.NewReaderSize(p.r, ReadBuf)
 
 	return p, nil
 }
@@ -111,9 +115,10 @@ func (p *pieceReader) ReadAt(b []byte, off int64) (n int, err error) {
 				return 0, xerrors.Errorf("closing backing reader: %w", err)
 			}
 			p.r = nil
+			p.br = nil
 		}
 
-		log.Debugw("pieceReader new stream", "piece", p.pieceCid, "at", p.rAt, "off", off-p.rAt)
+		log.Debugw("pieceReader new stream", "piece", p.pieceCid, "at", p.rAt, "off", off-p.rAt, "n", len(b))
 
 		if off > p.rAt {
 			stats.Record(p.ctx, metrics.DagStorePRSeekForwardBytes.M(off-p.rAt), metrics.DagStorePRSeekForwardCount.M(1))
@@ -123,6 +128,7 @@ func (p *pieceReader) ReadAt(b []byte, off int64) (n int, err error) {
 
 		p.rAt = off
 		p.r, _, err = p.api.FetchUnsealedPiece(p.ctx, p.pieceCid, uint64(p.rAt))
+		p.br = bufio.NewReaderSize(p.r, ReadBuf)
 		if err != nil {
 			return 0, xerrors.Errorf("getting backing reader: %w", err)
 		}
@@ -132,7 +138,7 @@ func (p *pieceReader) ReadAt(b []byte, off int64) (n int, err error) {
 	if off > p.rAt {
 		stats.Record(p.ctx, metrics.DagStorePRBytesDiscarded.M(off-p.rAt), metrics.DagStorePRDiscardCount.M(1))
 
-		n, err := io.CopyN(io.Discard, p.r, off-p.rAt)
+		n, err := io.CopyN(io.Discard, p.br, off-p.rAt)
 		p.rAt += n
 		if err != nil {
 			return 0, xerrors.Errorf("discarding read gap: %w", err)
@@ -145,7 +151,11 @@ func (p *pieceReader) ReadAt(b []byte, off int64) (n int, err error) {
 	}
 
 	// 4. Read!
-	n, err = p.r.Read(b)
+	n, err = io.ReadFull(p.br, b)
+	if n < len(b) {
+		log.Debugw("pieceReader short read", "piece", p.pieceCid, "at", p.rAt, "toEnd", int64(p.len)-p.rAt, "n", len(b), "read", n, "err", err)
+	}
+
 	p.rAt += int64(n)
 	return n, err
 }