diff --git a/caller.go b/caller.go
index a109fa0..c6e0a28 100644
--- a/caller.go
+++ b/caller.go
@@ -4,11 +4,13 @@ import (
 	"errors"
 	"fmt"
 	"reflect"
+	"sync"
 )
 
 type caller struct {
-	Func       reflect.Value
-	Args       []reflect.Type
+	sync.RWMutex
+	Func reflect.Value
+	Args []reflect.Type
 }
 
 func newCaller(f interface{}) (*caller, error) {
@@ -28,12 +30,15 @@ func newCaller(f interface{}) (*caller, error) {
 	}
 
 	return &caller{
-		Func:       fv,
-		Args:       args,
+		Func: fv,
+		Args: args,
 	}, nil
 }
 
 func (c *caller) GetArgs() []interface{} {
+	c.RLock()
+	defer c.RUnlock()
+
 	ret := make([]interface{}, len(c.Args))
 	for i, argT := range c.Args {
 		if argT.Kind() == reflect.Ptr {
@@ -46,6 +51,8 @@ func (c *caller) GetArgs() []interface{} {
 }
 
 func (c *caller) Call(args []interface{}) []reflect.Value {
+	c.RLock()
+	defer c.RUnlock()
 	var a []reflect.Value
 	diff := 0
 
diff --git a/client.go b/client.go
index ad9176e..eaf72e1 100644
--- a/client.go
+++ b/client.go
@@ -2,9 +2,10 @@ package socketio_client
 
 import (
 	"net/url"
-	"reflect"
 	"path"
+	"reflect"
 	"strings"
+	"sync"
 )
 
 type Options struct {
@@ -17,10 +18,11 @@ type Client struct {
 
 	conn *clientConn
 
-	events    map[string]*caller
-	acks      map[int]*caller
-	id        int
-	namespace string
+	eventsLock sync.RWMutex
+	events     map[string]*caller
+	acks       map[int]*caller
+	id         int
+	namespace  string
 }
 
 func NewClient(uri string, opts *Options) (client *Client, err error) {
@@ -29,10 +31,10 @@ func NewClient(uri string, opts *Options) (client *Client, err error) {
 	if err != nil {
 		return
 	}
-	url.Path = path.Join("/socket.io",url.Path)
+	url.Path = path.Join("/socket.io", url.Path)
 	url.Path = url.EscapedPath()
-	if strings.HasSuffix(url.Path,"socket.io"){
-		url.Path+="/"
+	if strings.HasSuffix(url.Path, "socket.io") {
+		url.Path += "/"
 	}
 	q := url.Query()
 	for k, v := range opts.Query {
@@ -63,7 +65,9 @@ func (client *Client) On(message string, f interface{}) (err error) {
 	if err != nil {
 		return
 	}
+	client.eventsLock.Lock()
 	client.events[message] = c
+	client.eventsLock.Unlock()
 	return
 }
 
@@ -147,7 +151,9 @@ func (client *Client) onPacket(decoder *decoder, packet *packet) ([]interface{},
 	default:
 		message = decoder.Message()
 	}
+	client.eventsLock.RLock()
 	c, ok := client.events[message]
+	client.eventsLock.RUnlock()
 	if !ok {
 		// If the message is not recognized by the server, the decoder.currentCloser
 		// needs to be closed otherwise the server will be stuck until the e
diff --git a/client_conn.go b/client_conn.go
index 118a984..000735a 100644
--- a/client_conn.go
+++ b/client_conn.go
@@ -181,6 +181,7 @@ func (c *clientConn) OnPacket(r *parser.PacketDecoder) {
 		t := c.getCurrent()
 		u := c.getUpgrade()
 		newWriter := t.NextWriter
+		c.writerLocker.Lock()
 		if u != nil {
 			if w, _ := t.NextWriter(message.MessageText, parser.NOOP); w != nil {
 				w.Close()
@@ -191,6 +192,7 @@ func (c *clientConn) OnPacket(r *parser.PacketDecoder) {
 			io.Copy(w, r)
 			w.Close()
 		}
+		c.writerLocker.Unlock()
 		fallthrough
 	case parser.PONG:
 		c.pingChan <- true