diff --git a/internal/native/client.go b/internal/native/client.go
index 8145444..5fbc783 100644
--- a/internal/native/client.go
+++ b/internal/native/client.go
@@ -31,11 +31,10 @@ import (
 
 type (
 	Client struct {
-		vu      modules.VU
-		key     ecdsa.PrivateKey
-		tok     session.Object
-		cli     *client.Client
-		bufsize int
+		vu  modules.VU
+		key ecdsa.PrivateKey
+		tok session.Object
+		cli *client.Client
 	}
 
 	PutResponse struct {
@@ -66,10 +65,9 @@ type (
 	}
 
 	PreparedObject struct {
-		vu      modules.VU
-		key     ecdsa.PrivateKey
-		cli     *client.Client
-		bufsize int
+		vu  modules.VU
+		key ecdsa.PrivateKey
+		cli *client.Client
 
 		hdr     object.Object
 		payload []byte
@@ -78,17 +76,6 @@ type (
 
 const defaultBufferSize = 64 * 1024
 
-func (c *Client) SetBufferSize(size int) {
-	if size < 0 {
-		panic("buffer size must be positive")
-	}
-	if size == 0 {
-		c.bufsize = defaultBufferSize
-	} else {
-		c.bufsize = size
-	}
-}
-
 func (c *Client) Put(containerID string, headers map[string]string, payload goja.ArrayBuffer, chunkSize int) PutResponse {
 	cliContainerID := parseContainerID(containerID)
 
@@ -116,7 +103,7 @@ func (c *Client) Put(containerID string, headers map[string]string, payload goja
 	o.SetOwnerID(&owner)
 	o.SetAttributes(attrs...)
 
-	resp, err := put(c.vu, c.bufsize, c.cli, &tok, &o, payload.Bytes(), chunkSize)
+	resp, err := put(c.vu, c.cli, &tok, &o, payload.Bytes(), chunkSize)
 	if err != nil {
 		return PutResponse{Success: false, Error: err.Error()}
 	}
@@ -176,7 +163,7 @@ func (c *Client) Get(containerID, objectID string) GetResponse {
 	prm.WithinSession(tok)
 
 	var objSize = 0
-	err = get(c.cli, prm, c.vu.Context(), c.bufsize, func(data []byte) {
+	err = get(c.cli, prm, c.vu.Context(), func(data []byte) {
 		objSize += len(data)
 	})
 	if err != nil {
@@ -194,10 +181,9 @@ func get(
 	cli *client.Client,
 	prm client.PrmObjectGet,
 	ctx context.Context,
-	bufSize int,
 	onDataChunk func(chunk []byte),
 ) error {
-	var buf = make([]byte, bufSize)
+	var buf = make([]byte, defaultBufferSize)
 
 	objectReader, err := cli.ObjectGetInit(ctx, prm)
 	if err != nil {
@@ -245,7 +231,7 @@ func (c *Client) VerifyHash(containerID, objectID, expectedHash string) VerifyHa
 	prm.WithinSession(tok)
 
 	hasher := sha256.New()
-	err = get(c.cli, prm, c.vu.Context(), c.bufsize, func(data []byte) {
+	err = get(c.cli, prm, c.vu.Context(), func(data []byte) {
 		hasher.Write(data)
 	})
 	if err != nil {
@@ -381,10 +367,9 @@ func (c *Client) Onsite(containerID string, payload goja.ArrayBuffer) PreparedOb
 	}
 
 	return PreparedObject{
-		vu:      c.vu,
-		key:     c.key,
-		cli:     c.cli,
-		bufsize: c.bufsize,
+		vu:  c.vu,
+		key: c.key,
+		cli: c.cli,
 
 		hdr:     *obj,
 		payload: data,
@@ -413,7 +398,7 @@ func (p PreparedObject) Put(headers map[string]string) PutResponse {
 		return PutResponse{Success: false, Error: err.Error()}
 	}
 
-	_, err = put(p.vu, p.bufsize, p.cli, nil, &obj, p.payload, 0)
+	_, err = put(p.vu, p.cli, nil, &obj, p.payload, 0)
 	if err != nil {
 		return PutResponse{Success: false, Error: err.Error()}
 	}
@@ -421,8 +406,12 @@ func (p PreparedObject) Put(headers map[string]string) PutResponse {
 	return PutResponse{Success: true, ObjectID: id.String()}
 }
 
-func put(vu modules.VU, bufSize int, cli *client.Client, tok *session.Object,
+func put(vu modules.VU, cli *client.Client, tok *session.Object,
 	hdr *object.Object, payload []byte, chunkSize int) (*client.ResObjectPut, error) {
+	bufSize := defaultBufferSize
+	if chunkSize > 0 {
+		bufSize = chunkSize
+	}
 	buf := make([]byte, bufSize)
 	rdr := bytes.NewReader(payload)
 	sz := rdr.Size()
diff --git a/internal/native/native.go b/internal/native/native.go
index 87b844b..f3357d2 100644
--- a/internal/native/native.go
+++ b/internal/native/native.go
@@ -133,10 +133,9 @@ func (n *Native) Connect(endpoint, hexPrivateKey string, dialTimeout, streamTime
 	cnrPutDuration, _ = registry.NewMetric("frostfs_cnr_put_duration", metrics.Trend, metrics.Time)
 
 	return &Client{
-		vu:      n.vu,
-		key:     pk.PrivateKey,
-		tok:     tok,
-		cli:     &cli,
-		bufsize: defaultBufferSize,
+		vu:  n.vu,
+		key: pk.PrivateKey,
+		tok: tok,
+		cli: &cli,
 	}, nil
 }