diff --git a/serial.go b/serial.go
index 0bfd77873..743cbfa1f 100755
--- a/serial.go
+++ b/serial.go
@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/arduino/arduino-create-agent/upload"
@@ -29,11 +30,14 @@ type serialhub struct {
 
 	// Unregister requests from connections.
 	unregister chan *serport
+
+	mu sync.Mutex
 }
 
 type SpPortList struct {
 	Ports   []SpPortItem
 	Network bool
+	mu      sync.Mutex `json:"-"`
 }
 
 type SpPortItem struct {
@@ -72,15 +76,19 @@ func (sh *serialhub) run() {
 	for {
 		select {
 		case p := <-sh.register:
+			sh.mu.Lock()
 			//log.Print("Registering a port: ", p.portConf.Name)
 			h.broadcastSys <- []byte("{\"Cmd\":\"Open\",\"Desc\":\"Got register/open on port.\",\"Port\":\"" + p.portConf.Name + "\",\"Baud\":" + strconv.Itoa(p.portConf.Baud) + ",\"BufferType\":\"" + p.BufferType + "\"}")
 			sh.ports[p] = true
+			sh.mu.Unlock()
 		case p := <-sh.unregister:
+			sh.mu.Lock()
 			//log.Print("Unregistering a port: ", p.portConf.Name)
 			h.broadcastSys <- []byte("{\"Cmd\":\"Close\",\"Desc\":\"Got unregister/close on port.\",\"Port\":\"" + p.portConf.Name + "\",\"Baud\":" + strconv.Itoa(p.portConf.Baud) + "}")
 			delete(sh.ports, p)
 			close(p.sendBuffered)
 			close(p.sendNoBuf)
+			sh.mu.Unlock()
 		case wr := <-sh.write:
 			// if user sent in the commands as one text mode line
 			write(wr)
@@ -102,13 +110,17 @@ func write(wr writeRequest) {
 
 // spList broadcasts a Json representation of the ports found
 func spList(network bool) {
-	var list SpPortList
+	var ls []byte
+	var err error
 	if network {
-		list = NetworkPorts
+		NetworkPorts.mu.Lock()
+		ls, err = json.MarshalIndent(NetworkPorts, "", "\t")
+		NetworkPorts.mu.Unlock()
 	} else {
-		list = SerialPorts
+		SerialPorts.mu.Lock()
+		ls, err = json.MarshalIndent(SerialPorts, "", "\t")
+		SerialPorts.mu.Unlock()
 	}
-	ls, err := json.MarshalIndent(list, "", "\t")
 	if err != nil {
 		//log.Println(err)
 		h.broadcastSys <- []byte("Error creating json on port list " +
@@ -120,10 +132,14 @@ func spList(network bool) {
 
 // discoverLoop periodically update the list of ports found
 func discoverLoop() {
+	SerialPorts.mu.Lock()
 	SerialPorts.Network = false
 	SerialPorts.Ports = make([]SpPortItem, 0)
+	SerialPorts.mu.Unlock()
+	NetworkPorts.mu.Lock()
 	NetworkPorts.Network = true
 	NetworkPorts.Ports = make([]SpPortItem, 0)
+	NetworkPorts.mu.Unlock()
 
 	go func() {
 		for {
@@ -184,13 +200,13 @@ func spListDual(network bool) {
 	// to append the open/close state, baud rates, etc to make
 	// a super clean nice list to send back to browser
 	n := len(list)
-	spl := SpPortList{make([]SpPortItem, n, n), network}
+	spl := make([]SpPortItem, n)
 
 	ctr := 0
 
 	for _, item := range list {
 
-		spl.Ports[ctr] = SpPortItem{
+		spl[ctr] = SpPortItem{
 			Name:            item.Name,
 			SerialNumber:    item.ISerial,
 			DeviceClass:     item.DeviceClass,
@@ -209,17 +225,21 @@ func spListDual(network bool) {
 
 		if isFound {
 			// we found our port
-			spl.Ports[ctr].IsOpen = true
-			spl.Ports[ctr].Baud = myport.portConf.Baud
-			spl.Ports[ctr].BufferAlgorithm = myport.BufferType
+			spl[ctr].IsOpen = true
+			spl[ctr].Baud = myport.portConf.Baud
+			spl[ctr].BufferAlgorithm = myport.BufferType
 		}
 		ctr++
 	}
 
 	if network {
-		NetworkPorts = spl
+		NetworkPorts.mu.Lock()
+		NetworkPorts.Ports = spl
+		NetworkPorts.mu.Unlock()
 	} else {
-		SerialPorts = spl
+		SerialPorts.mu.Lock()
+		SerialPorts.Ports = spl
+		SerialPorts.mu.Unlock()
 	}
 }
 
diff --git a/seriallist.go b/seriallist.go
index 4e26f4dee..fc02295dc 100755
--- a/seriallist.go
+++ b/seriallist.go
@@ -71,6 +71,8 @@ func GetList(network bool) ([]OsSerialPort, error) {
 
 func findPortByName(portname string) (*serport, bool) {
 	portnamel := strings.ToLower(portname)
+	sh.mu.Lock()
+	defer sh.mu.Unlock()
 	for port := range sh.ports {
 		if strings.ToLower(port.portConf.Name) == portnamel {
 			// we found our port
@@ -80,14 +82,3 @@ func findPortByName(portname string) (*serport, bool) {
 	}
 	return nil, false
 }
-
-func findPortByNameRerun(portname string, network bool) (OsSerialPort, bool) {
-	portnamel := strings.ToLower(portname)
-	list, _ := GetList(network)
-	for _, item := range list {
-		if strings.ToLower(item.Name) == portnamel {
-			return item, true
-		}
-	}
-	return OsSerialPort{}, false
-}