README      |  2 +-
 diff.go     | 10 +++-------
 dirsizer.go | 25 ++++++++++++++++++++-----
 go.mod      |  2 ++
 go.sum      |  2 ++
 index.go    |  7 +------
 main.go     |  3 +--
 reader.go   | 23 ++++++++++++++++-------
 writer.go   | 26 ++++++++++++++++++++------

diff --git a/README b/README
index 358d5302a98ae9b877e6acf1c950d413e096a065959e58f8d3a631cabf2c1a37..8c52b350ce33c6e2b4f83ae2dd4fc980b342b8d3fa0b79ac2917988101f77477 100644
--- a/README
+++ b/README
@@ -18,7 +18,7 @@ memory, but that takes 2-3 GiBs of memory, that is huge amount. Moreover
 it fully loads it to perform any basic searches. So current
 implementation uses temporary files and heavy use of data streaming.
 
-Its storage format is trivial:
+Its storage format is simple: Zstandard-compressed list of records:
 
 * 16-bit BE size of the following name
 * entity (file, directory, symbolic link, etc) name itself.
diff --git a/diff.go b/diff.go
index 61ba1ac9f83e9f80cb3ac2a7b81e88079e1e9a2d3a8e8afabd34f0485b739d9f..dda4fd9ded52ee8109d30cbf1974527600de590be43819023d0df4ab8fbb91f4 100644
--- a/diff.go
+++ b/diff.go
@@ -105,7 +105,7 @@ 	adds := make([][]string, 0, len(addsNames)+len(rens))
 	mods := make([]*Ent, 0, len(modsNames)+len(rens))
 	if len(rens) > 0 {
 		sort.Sort(BySrc(rens))
-		go reader(bufio.NewReaderSize(db, 1<<17), entsReader)
+		go reader(db, entsReader)
 		var ent Ent
 		var ok, met bool
 		for {
@@ -183,7 +183,7 @@ 	defer os.Remove(tmp0.Name())
 	entsReader = make(chan Ent, 1<<10)
 	entsDirSizer := make(chan Ent, 1<<10)
 	entsWriter := make(chan Ent, 1<<10)
-	go reader(bufio.NewReaderSize(db, 1<<17), entsReader)
+	go reader(db, entsReader)
 
 	dirSizerJob := make(chan struct{})
 	var dirSizes []int64
@@ -193,10 +193,9 @@ 		dirSizer(&dirSizes, 1, sinkBack, entsDirSizer, entsWriter)
 		close(dirSizerJob)
 	}()
 
-	bw := bufio.NewWriterSize(tmp0, 1<<17)
 	writerJob := make(chan struct{})
 	go func() {
-		writer(bw, entsWriter)
+		writer(tmp0, entsWriter)
 		close(writerJob)
 	}()
 
@@ -243,9 +242,6 @@ 	close(entsDirSizer)
 	<-dirSizerJob
 	close(entsWriter)
 	<-writerJob
-	if err = bw.Flush(); err != nil {
-		log.Fatalln(err)
-	}
 
 	tmp1 := applyDirSizes(tmp0, dirSizes)
 	tmp0.Close()
diff --git a/dirsizer.go b/dirsizer.go
index b4f5b4e51c46905addae4a0e5a061a445d23f1a3d6e0e6ce0967c2f36d221a93..fda37f4fe46098cf687690e5e03984aba77f952ed5814359e94deefcccbbbdb3 100644
--- a/dirsizer.go
+++ b/dirsizer.go
@@ -6,6 +6,8 @@ 	"encoding/binary"
 	"io"
 	"log"
 	"os"
+
+	"github.com/klauspost/compress/zstd"
 )
 
 func dirSizer(dirSizes *[]int64, depth int, sinkBack, sinkIn, sinkOut chan Ent) (curSize int64) {
@@ -51,11 +53,22 @@ 	if err != nil {
 		log.Fatalln(err)
 	}
 
-	br := bufio.NewReaderSize(src, 1<<17)
+	compR, err := zstd.NewReader(src)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	br := bufio.NewReaderSize(compR, 1<<17)
+
+	compW, err := zstd.NewWriter(tmp,
+		zstd.WithEncoderLevel(zstd.SpeedBestCompression))
+	if err != nil {
+		log.Fatalln(err)
+	}
+	bw := bufio.NewWriterSize(compW, 1<<17)
+
 	num := make([]byte, 8)
 	var nameLen int
 	name := make([]byte, 0, 1<<16)
-	bw := bufio.NewWriterSize(tmp, 1<<17)
 	var dirIdx int
 	for {
 		if _, err = io.ReadFull(br, num[:2]); err != nil {
@@ -67,9 +80,7 @@ 		}
 		mustWrite(bw, num[:2])
 		nameLen = int(binary.BigEndian.Uint16(num[:2]))
 		name = name[:nameLen]
-		if _, err = io.ReadFull(br, name); err != nil {
-			log.Fatalln(err)
-		}
+		mustReadFull(br, name)
 		mustWrite(bw, name)
 		if _, err = io.CopyN(bw, br, 1+8); err != nil {
 			log.Fatalln(err)
@@ -90,5 +101,9 @@ 	}
 	if err = bw.Flush(); err != nil {
 		log.Fatalln(err)
 	}
+	if err = compW.Close(); err != nil {
+		log.Fatalln(err)
+	}
+	compR.Close()
 	return tmp
 }
diff --git a/go.mod b/go.mod
index f8654fc71f5b20da772216ab5c99b8f3d5c0d4e6f80285b811eb9ef3a932a85b..7d95a307792df055072c49908b254f1d7104f6872fe699f79df78e2f5f315f2c 100644
--- a/go.mod
+++ b/go.mod
@@ -3,3 +3,5 @@
 go 1.18
 
 require github.com/dustin/go-humanize v1.0.0
+
+require github.com/klauspost/compress v1.15.9
diff --git a/go.sum b/go.sum
index 4f89ea40df43dd72a9ee4bb17b5304a77cd360409cd05cc9431c6210cfbb63c5..568acaac67a8ceacd643b3927d665ea337dccc412d49088ad5449810553ca241 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,4 @@
 github.com/dustin/go-humanize v1.0.0 h1:VSnTsYCnlFHaM2/igO1h6X3HA71jcobQuxemgkq4zYo=
 github.com/dustin/go-humanize v1.0.0/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
+github.com/klauspost/compress v1.15.9 h1:wKRjX6JRtDdrE9qwa4b/Cip7ACOshUI4smpCQanqjSY=
+github.com/klauspost/compress v1.15.9/go.mod h1:PhcZ0MbTNciWF3rruxRgKxI5NkcHHrHUDtV4Yw2GlzU=
diff --git a/index.go b/index.go
index c6fa5398b74fb4ace31a4f09587b8579e3b9642d55040d46e92a1f37fe5e99fb..c05e4c0b84d35c2d6d49beede0faf14c8f985fd98f2d42c1bf11a336f2f49381 100644
--- a/index.go
+++ b/index.go
@@ -1,7 +1,6 @@
 package main
 
 import (
-	"bufio"
 	"fmt"
 	"log"
 	"os"
@@ -25,10 +24,9 @@ 		dirSizer(&dirSizes, 1, sinkBack, entsWalker, entsWriter)
 		close(dirSizerJob)
 	}()
 
-	bw := bufio.NewWriterSize(tmp0, 1<<17)
 	writerJob := make(chan struct{})
 	go func() {
-		writer(bw, entsWriter)
+		writer(tmp0, entsWriter)
 		close(writerJob)
 	}()
 
@@ -45,9 +43,6 @@ 	close(entsWalker)
 	<-dirSizerJob
 	close(entsWriter)
 	<-writerJob
-	if err = bw.Flush(); err != nil {
-		log.Fatalln(err)
-	}
 
 	tmp1 := applyDirSizes(tmp0, dirSizes)
 	tmp0.Close()
diff --git a/main.go b/main.go
index a5fcb41451e9410c3be3d629ba89dea6d354c675abe9fd2fa7e0879514b10095..c8615fdd85d4f2b76db67f755348feb0a9baf32c17bfdab0b72473fdb634dd58 100644
--- a/main.go
+++ b/main.go
@@ -1,7 +1,6 @@
 package main
 
 import (
-	"bufio"
 	"flag"
 	"log"
 	"os"
@@ -64,7 +63,7 @@ 	if err != nil {
 		log.Fatalln(err)
 	}
 	entsReader := make(chan Ent, 1<<10)
-	go reader(bufio.NewReaderSize(db, 1<<17), entsReader)
+	go reader(db, entsReader)
 
 	entsPrinter := make(chan Ent, 1<<10)
 	printerJob := make(chan struct{})
diff --git a/reader.go b/reader.go
index 269fc3295dac975ee17b8a4007c9995da5813562f989a1ff4ce3f92366daa7eb..8900c26a75b3fd91ba83e1d45f9d923436981f3e84a45ea784cb151c474d50b4 100644
--- a/reader.go
+++ b/reader.go
@@ -1,9 +1,12 @@
 package main
 
 import (
+	"bufio"
 	"encoding/binary"
 	"io"
 	"log"
+
+	"github.com/klauspost/compress/zstd"
 )
 
 func mustReadFull(r io.Reader, buf []byte) {
@@ -12,15 +15,20 @@ 		log.Fatalln(err)
 	}
 }
 
-func reader(r io.Reader, sink chan Ent) {
-	var err error
+func reader(src io.Reader, sink chan Ent) {
+	comp, err := zstd.NewReader(src)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	br := bufio.NewReaderSize(comp, 1<<17)
+
 	num := make([]byte, 8)
 	var cols []string
 	var namePrev string
 	var nameLen uint16
 	var depth, depthPrev uint8
 	for {
-		_, err = io.ReadFull(r, num[:2])
+		_, err = io.ReadFull(br, num[:2])
 		if err != nil {
 			if err == io.EOF {
 				break
@@ -29,13 +37,13 @@ 			log.Fatalln(err)
 		}
 		nameLen = binary.BigEndian.Uint16(num[:2])
 		nameRaw := make([]byte, nameLen)
-		mustReadFull(r, nameRaw)
+		mustReadFull(br, nameRaw)
 		name := string(nameRaw)
-		mustReadFull(r, num[:1])
+		mustReadFull(br, num[:1])
 		depth = uint8(num[0])
-		mustReadFull(r, num)
+		mustReadFull(br, num)
 		ent := Ent{mtime: int64(binary.BigEndian.Uint64(num))}
-		mustReadFull(r, num)
+		mustReadFull(br, num)
 		ent.size = int64(binary.BigEndian.Uint64(num))
 		if depth > depthPrev {
 			cols = append(cols, namePrev[:len(namePrev)-1])
@@ -48,4 +56,5 @@ 		namePrev = name
 		depthPrev = depth
 	}
 	close(sink)
+	comp.Close()
 }
diff --git a/writer.go b/writer.go
index e12a19c0d7f2103ae9c88e4c4f3c237bb3d03f62819ea98eb33c93210f221256..75b82e57abc5e88fff375e6c1a4a69ae1335b4e2ce944ad401c940ee08e3c8e1 100644
--- a/writer.go
+++ b/writer.go
@@ -1,9 +1,12 @@
 package main
 
 import (
+	"bufio"
 	"encoding/binary"
 	"io"
 	"log"
+
+	"github.com/klauspost/compress/zstd"
 )
 
 func mustWrite(w io.Writer, buf []byte) {
@@ -12,7 +15,12 @@ 		log.Fatalln(err)
 	}
 }
 
-func writer(w io.Writer, sink chan Ent) {
+func writer(dst io.Writer, sink chan Ent) {
+	comp, err := zstd.NewWriter(dst)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	bw := bufio.NewWriterSize(comp, 1<<17)
 	num := make([]byte, 8)
 	var name string
 	for ent := range sink {
@@ -21,15 +29,21 @@ 		if len(ent.name) >= 1<<16 {
 			panic("too long")
 		}
 		binary.BigEndian.PutUint16(num[:2], uint16(len(name)))
-		mustWrite(w, num[:2])
-		mustWrite(w, []byte(name))
+		mustWrite(bw, num[:2])
+		mustWrite(bw, []byte(name))
 		if len(ent.name) >= 1<<8 {
 			panic("too deep")
 		}
-		mustWrite(w, []byte{byte(len(ent.name) - 1)})
+		mustWrite(bw, []byte{byte(len(ent.name) - 1)})
 		binary.BigEndian.PutUint64(num, uint64(ent.mtime))
-		mustWrite(w, num)
+		mustWrite(bw, num)
 		binary.BigEndian.PutUint64(num, uint64(ent.size))
-		mustWrite(w, num)
+		mustWrite(bw, num)
+	}
+	if err = bw.Flush(); err != nil {
+		log.Fatalln(err)
+	}
+	if err = comp.Close(); err != nil {
+		log.Fatalln(err)
 	}
 }