Can't bind hex values in go sql?

testhex.go

package main

import (
	"github.com/jmoiron/sqlx"
	_ "github.com/lib/pq"
)

type Result struct {
	Testhex string
}

func main(){
	var err error

	db, err := sqlx.Connect("postgres", "dbname=testhex sslmode=disable")
	if err != nil {
		panic(err)
	}

	var result Result
	err = db.Get(&result, "select testhex from testhex where testhex = $1", `\x123456`)
	if err != nil {
		panic(err) // no rows?
	}
}

testhex.sql

create table testhex (testhex bytea);
insert into testhex (testhex) values ('\x123456');