diff --git a/armor.go b/armor.go
index ac8a233..0e13716 100644
--- a/armor.go
+++ b/armor.go
@@ -35,12 +35,13 @@ type (
 	}
 
 	TLS struct {
-		Address  string `yaml:"address"`
-		CertFile string `yaml:"cert_file"`
-		KeyFile  string `yaml:"key_file"`
-		Auto     bool   `yaml:"auto"`
-		CacheDir string `yaml:"cache_dir"`
-		Email    string `yaml:"email"`
+		Address      string `yaml:"address"`
+		CertFile     string `yaml:"cert_file"`
+		KeyFile      string `yaml:"key_file"`
+		Auto         bool   `yaml:"auto"`
+		CacheDir     string `yaml:"cache_dir"`
+		Email        string `yaml:"email"`
+		DirectoryURL string `yaml:"directory_url"`
 	}
 
 	Admin struct {
diff --git a/http/http.go b/http/http.go
index 64c42a4..b762cde 100644
--- a/http/http.go
+++ b/http/http.go
@@ -11,6 +11,7 @@ import (
 	"github.com/labstack/echo"
 	"github.com/labstack/gommon/log"
 	homedir "github.com/mitchellh/go-homedir"
+	"golang.org/x/crypto/acme"
 	"golang.org/x/crypto/acme/autocert"
 )
 
@@ -46,6 +47,10 @@ func Init(a *armor.Armor) (h *HTTP) {
 			WriteTimeout: a.WriteTimeout * time.Second,
 		}
 		e.AutoTLSManager.Email = a.TLS.Email
+		e.AutoTLSManager.Client = new(acme.Client)
+		if a.TLS.DirectoryURL != "" {
+			e.AutoTLSManager.Client.DirectoryURL = a.TLS.DirectoryURL
+		}
 	}
 	e.Logger = h.logger
 
@@ -90,6 +95,9 @@ func (h *HTTP) StartTLS() error {
 	s.TLSConfig.NextProtos = append(s.TLSConfig.NextProtos, "h2")
 
 	if a.TLS.Auto {
+		// Enable the "http-01" challenge
+		e.Server.Handler = e.AutoTLSManager.HTTPHandler(e.Server.Handler)
+
 		hosts := []string{}
 		for host := range a.Hosts {
 			hosts = append(hosts, host)
diff --git a/website/content/guide/configuration.md b/website/content/guide/configuration.md
index 399b3e0..774f9f1 100644
--- a/website/content/guide/configuration.md
+++ b/website/content/guide/configuration.md
@@ -28,6 +28,7 @@ Name | Type | Description
 `auto` | bool | Enable automatic certificates from https://letsencrypt.org
 `cache_dir` | string | Cache directory to store certificates from https://letsencrypt.org. Default value `~/.armor/cache`.
 `email` | string | Email optionally specifies a contact email address.
+`directory_url` | string | Defines the ACME CA directory endpoint. If empty, LetsEncryptURL is used (acme.LetsEncryptURL).
 
 `hosts`