diff --git a/cli/join.go b/cli/join.go
index 403b9c150b..edf4f90802 100644
--- a/cli/join.go
+++ b/cli/join.go
@@ -3,7 +3,7 @@ package cli
 import (
 	"math/rand"
 	"net"
-	"regexp"
+	"strconv"
 	"time"
 
 	log "github.com/Sirupsen/logrus"
@@ -17,8 +17,8 @@ func checkAddrFormat(addr string) bool {
 	if err != nil {
 		return false
 	}
-	m, _ := regexp.MatchString("^[0-9]{1,5}$", port)
-	return m
+	portNum, err := strconv.Atoi(port)
+	return err == nil && portNum >= 0 && portNum <= 65535
 }
 
 func join(c *cli.Context) {
diff --git a/cli/join_test.go b/cli/join_test.go
index 9680b2f831..b7db39a91b 100644
--- a/cli/join_test.go
+++ b/cli/join_test.go
@@ -24,6 +24,11 @@ func TestCheckAddrFormat(t *testing.T) {
 	assert.True(t, checkAddrFormat("1.1.1.1:1111"))
 	assert.True(t, checkAddrFormat("hostname:1111"))
 	assert.True(t, checkAddrFormat("host-name_42:1111"))
+	assert.False(t, checkAddrFormat("1.1.1.1:-1"))
+	assert.True(t, checkAddrFormat("1.1.1.1:65535"))
+	assert.False(t, checkAddrFormat("1.1.1.1:65536"))
+	assert.False(t, checkAddrFormat("1.1.1.1: 4000"))
+	assert.False(t, checkAddrFormat("1.1.1.1:m2"))
 	assert.True(t, checkAddrFormat("[2001:db8:0:f101::3]:2375"))
 	assert.False(t, checkAddrFormat("2001:db8:0:f101::3:2375"))
 	assert.False(t, checkAddrFormat("[2001:db8:0:f101::3]:3:2375"))