diff --git a/src/pkg/websocket/hixie.go b/src/pkg/websocket/hixie.go
index b755a5c6a6..43de8a7800 100644
--- a/src/pkg/websocket/hixie.go
+++ b/src/pkg/websocket/hixie.go
@@ -235,6 +235,8 @@ func (handler *hixiFrameHandler) HandleFrame(frame frameReader) (r frameReader,
 }
 
 func (handler *hixiFrameHandler) WriteClose(_ int) (err os.Error) {
+	handler.conn.wio.Lock()
+	defer handler.conn.wio.Unlock()
 	closingFrame := []byte{'\xff', '\x00'}
 	handler.conn.buf.Write(closingFrame)
 	return handler.conn.buf.Flush()
diff --git a/src/pkg/websocket/hybi.go b/src/pkg/websocket/hybi.go
index cad47182d6..c4d990d6d8 100644
--- a/src/pkg/websocket/hybi.go
+++ b/src/pkg/websocket/hybi.go
@@ -288,6 +288,8 @@ func (handler *hybiFrameHandler) HandleFrame(frame frameReader) (r frameReader,
 }
 
 func (handler *hybiFrameHandler) WriteClose(status int) (err os.Error) {
+	handler.conn.wio.Lock()
+	defer handler.conn.wio.Unlock()
 	w, err := handler.conn.frameWriterFactory.NewFrameWriter(CloseFrame)
 	if err != nil {
 		return err
@@ -300,6 +302,8 @@ func (handler *hybiFrameHandler) WriteClose(status int) (err os.Error) {
 }
 
 func (handler *hybiFrameHandler) WritePong(msg []byte) (n int, err os.Error) {
+	handler.conn.wio.Lock()
+	defer handler.conn.wio.Unlock()
 	w, err := handler.conn.frameWriterFactory.NewFrameWriter(PongFrame)
 	if err != nil {
 		return 0, err
diff --git a/src/pkg/websocket/websocket.go b/src/pkg/websocket/websocket.go
index d57d1149c8..1855705c99 100644
--- a/src/pkg/websocket/websocket.go
+++ b/src/pkg/websocket/websocket.go
@@ -15,6 +15,7 @@ import (
 	"json"
 	"net"
 	"os"
+	"sync"
 	"url"
 )
 
@@ -147,9 +148,11 @@ type Conn struct {
 	buf *bufio.ReadWriter
 	rwc io.ReadWriteCloser
 
+	rio sync.Mutex
 	frameReaderFactory
 	frameReader
 
+	wio sync.Mutex
 	frameWriterFactory
 
 	frameHandler
@@ -163,6 +166,8 @@ type Conn struct {
 // will read the rest of the frame data.
 // it reads Text frame or Binary frame.
 func (ws *Conn) Read(msg []byte) (n int, err os.Error) {
+	ws.rio.Lock()
+	defer ws.rio.Unlock()
 again:
 	if ws.frameReader == nil {
 		frame, err := ws.frameReaderFactory.NewFrameReader()
@@ -191,6 +196,8 @@ again:
 // Write implements the io.Writer interface:
 // it writes data as a frame to the WebSocket connection.
 func (ws *Conn) Write(msg []byte) (n int, err os.Error) {
+	ws.wio.Lock()
+	defer ws.wio.Unlock()
 	w, err := ws.frameWriterFactory.NewFrameWriter(ws.PayloadType)
 	if err != nil {
 		return 0, err
@@ -279,6 +286,8 @@ func (cd Codec) Send(ws *Conn, v interface{}) (err os.Error) {
 	if err != nil {
 		return err
 	}
+	ws.wio.Lock()
+	defer ws.wio.Unlock()
 	w, err := ws.frameWriterFactory.NewFrameWriter(payloadType)
 	_, err = w.Write(data)
 	w.Close()
@@ -287,6 +296,8 @@ func (cd Codec) Send(ws *Conn, v interface{}) (err os.Error) {
 
 // Receive receives single frame from ws, unmarshaled by cd.Unmarshal and stores in v.
 func (cd Codec) Receive(ws *Conn, v interface{}) (err os.Error) {
+	ws.rio.Lock()
+	defer ws.rio.Unlock()
 	if ws.frameReader != nil {
 		_, err = io.Copy(ioutil.Discard, ws.frameReader)
 		if err != nil {