generate a random bool in go

What's the fastest way to generate a random bool in go ?

currently I'm doing like this :

package main

import (
    "fmt"
    "math/rand"
    "time"
)

// random generator
var src = rand.NewSource(time.Now().UnixNano())
var r = rand.New(src)

func main() {
    for i := 0; i < 100; i++ {
        // generate a random boolean and print it 
        fmt.Printf("bool: %s\n", r.Intn(2) != 0)
    }
}

How can I improve this ?