diff --git a/internal/common/tls.go b/internal/common/tls.go
index fb54e97..3953992 100644
--- a/internal/common/tls.go
+++ b/internal/common/tls.go
@@ -2,6 +2,7 @@ package common
 
 import (
 	"encoding/binary"
+	"errors"
 	"io"
 	"net"
 	"sync"
@@ -94,6 +95,9 @@ func (tls *TLSConn) Read(buffer []byte) (n int, err error) {
 
 func (tls *TLSConn) Write(in []byte) (n int, err error) {
 	msgLen := len(in)
+	if msgLen > 1<<14+256 { // https://tools.ietf.org/html/rfc8446#section-5.2
+		return 0, errors.New("message is too long")
+	}
 	writeBuf := tls.writeBufPool.Get().(*[]byte)
 	*writeBuf = append(*writeBuf, byte(msgLen>>8), byte(msgLen&0xFF))
 	*writeBuf = append(*writeBuf, in...)
diff --git a/internal/multiplex/obfs_test.go b/internal/multiplex/obfs_test.go
index 2dad728..76ba3bc 100644
--- a/internal/multiplex/obfs_test.go
+++ b/internal/multiplex/obfs_test.go
@@ -138,7 +138,7 @@ func BenchmarkObfs(b *testing.B) {
 		testPayload,
 	}
 
-	obfsBuf := make([]byte, defaultSendRecvBufSize)
+	obfsBuf := make([]byte, len(testPayload)*2)
 
 	var key [32]byte
 	rand.Read(key[:])
@@ -211,7 +211,7 @@ func BenchmarkDeobfs(b *testing.B) {
 		testPayload,
 	}
 
-	obfsBuf := make([]byte, defaultSendRecvBufSize)
+	obfsBuf := make([]byte, len(testPayload)*2)
 
 	var key [32]byte
 	rand.Read(key[:])
diff --git a/internal/multiplex/recvBuffer.go b/internal/multiplex/recvBuffer.go
index 63f1f6f..a8aed87 100644
--- a/internal/multiplex/recvBuffer.go
+++ b/internal/multiplex/recvBuffer.go
@@ -25,4 +25,4 @@ type recvBuffer interface {
 // size we want the amount of unread data in buffer to grow before recvBuffer.Write blocks.
 // If the buffer grows larger than what the system's memory can offer at the time of recvBuffer.Write,
 // a panic will happen.
-const recvBufferSizeLimit = defaultSendRecvBufSize << 12
+const recvBufferSizeLimit = 1 << 31
diff --git a/internal/multiplex/session.go b/internal/multiplex/session.go
index 6abc90e..b9d8540 100644
--- a/internal/multiplex/session.go
+++ b/internal/multiplex/session.go
@@ -13,10 +13,9 @@ import (
 )
 
 const (
-	acceptBacklog = 1024
-	// TODO: will this be a signature?
-	defaultSendRecvBufSize   = 20480
+	acceptBacklog            = 1024
 	defaultInactivityTimeout = 30 * time.Second
+	defaultMaxOnWireSize     = 1<<14 + 256 // https://tools.ietf.org/html/rfc8446#section-5.2
 )
 
 var ErrBrokenSession = errors.New("broken session")
@@ -40,12 +39,6 @@ type SessionConfig struct {
 	// maximum size of an obfuscated frame, including headers and overhead
 	MsgOnWireSizeLimit int
 
-	// StreamSendBufferSize sets the buffer size used to send data from a Stream (Stream.obfsBuf)
-	StreamSendBufferSize int
-	// ConnReceiveBufferSize sets the buffer size used to receive data from an underlying Conn (allocated in
-	// switchboard.deplex)
-	ConnReceiveBufferSize int
-
 	// InactivityTimeout sets the duration a Session waits while it has no active streams before it closes itself
 	InactivityTimeout time.Duration
 }
@@ -87,6 +80,11 @@ type Session struct {
 	// the max size passed to Write calls before it splits it into multiple frames
 	// i.e. the max size a piece of data can fit into a Frame.Payload
 	maxStreamUnitWrite int
+	// streamSendBufferSize sets the buffer size used to send data from a Stream (Stream.obfsBuf)
+	streamSendBufferSize int
+	// connReceiveBufferSize sets the buffer size used to receive data from an underlying Conn (allocated in
+	// switchboard.deplex)
+	connReceiveBufferSize int
 }
 
 func MakeSession(id uint32, config SessionConfig) *Session {
@@ -103,23 +101,19 @@ func MakeSession(id uint32, config SessionConfig) *Session {
 	if config.Valve == nil {
 		sesh.Valve = UNLIMITED_VALVE
 	}
-	if config.StreamSendBufferSize <= 0 {
-		sesh.StreamSendBufferSize = defaultSendRecvBufSize
-	}
-	if config.ConnReceiveBufferSize <= 0 {
-		sesh.ConnReceiveBufferSize = defaultSendRecvBufSize
-	}
 	if config.MsgOnWireSizeLimit <= 0 {
-		sesh.MsgOnWireSizeLimit = defaultSendRecvBufSize - 1024
+		sesh.MsgOnWireSizeLimit = defaultMaxOnWireSize
 	}
 	if config.InactivityTimeout == 0 {
 		sesh.InactivityTimeout = defaultInactivityTimeout
 	}
-	// todo: validation. this must be smaller than StreamSendBufferSize
-	sesh.maxStreamUnitWrite = sesh.MsgOnWireSizeLimit - frameHeaderLength - sesh.Obfuscator.maxOverhead
+
+	sesh.maxStreamUnitWrite = sesh.MsgOnWireSizeLimit - frameHeaderLength - sesh.maxOverhead
+	sesh.streamSendBufferSize = sesh.MsgOnWireSizeLimit
+	sesh.connReceiveBufferSize = 20480 // for backwards compatibility
 
 	sesh.streamObfsBufPool = sync.Pool{New: func() interface{} {
-		b := make([]byte, sesh.StreamSendBufferSize)
+		b := make([]byte, sesh.streamSendBufferSize)
 		return &b
 	}}
 
diff --git a/internal/multiplex/switchboard.go b/internal/multiplex/switchboard.go
index 84e43c9..829d944 100644
--- a/internal/multiplex/switchboard.go
+++ b/internal/multiplex/switchboard.go
@@ -159,7 +159,7 @@ func (sb *switchboard) closeAll() {
 // deplex function costantly reads from a TCP connection
 func (sb *switchboard) deplex(connId uint32, conn net.Conn) {
 	defer conn.Close()
-	buf := make([]byte, sb.session.ConnReceiveBufferSize)
+	buf := make([]byte, sb.session.connReceiveBufferSize)
 	for {
 		n, err := conn.Read(buf)
 		sb.valve.rxWait(n)
diff --git a/internal/test/integration_test.go b/internal/test/integration_test.go
index e4072e0..187507f 100644
--- a/internal/test/integration_test.go
+++ b/internal/test/integration_test.go
@@ -321,7 +321,7 @@ func TestTCPSingleplex(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	const echoMsgLen = 16384
+	const echoMsgLen = 1 << 16
 	go serveTCPEcho(proxyFromCkServerL)
 
 	proxyConn1, err := proxyToCkClientD.Dial("", "")