diff --git a/acme/client.go b/acme/client.go
index adb17a5e..b7e33152 100644
--- a/acme/client.go
+++ b/acme/client.go
@@ -253,7 +253,7 @@ func (c *Client) requestCertificates(challenges []*authorizationResource) ([]Cer
 			return nil, err
 		}
 		csrString := base64.URLEncoding.EncodeToString(csr)
-		jsonBytes, err := json.Marshal(csrMessage{Csr: csrString})
+		jsonBytes, err := json.Marshal(csrMessage{Csr: csrString, Authorizations: []string{authz.AuthURL}})
 		if err != nil {
 			return nil, err
 		}
diff --git a/acme/messages.go b/acme/messages.go
index 609e8b70..1ee1377a 100644
--- a/acme/messages.go
+++ b/acme/messages.go
@@ -58,7 +58,8 @@ type challenge struct {
 }
 
 type csrMessage struct {
-	Csr string `json:"csr"`
+	Csr            string   `json:"csr"`
+	Authorizations []string `json:"authorizations"`
 }
 
 // CertificateResource represents a CA issued certificate.