diff --git a/acme/tls_alpn_challenge.go b/acme/tls_alpn_challenge.go
index d8035199..cc70c350 100644
--- a/acme/tls_alpn_challenge.go
+++ b/acme/tls_alpn_challenge.go
@@ -12,8 +12,8 @@ import (
 )
 
 // idPeAcmeIdentifierV1 is the SMI Security for PKIX Certification Extension OID referencing the ACME extension.
-// Reference: https://tools.ietf.org/html/draft-ietf-acme-tls-alpn-01#section-5.1
-var idPeAcmeIdentifierV1 = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 1, 30, 1}
+// Reference: https://tools.ietf.org/html/draft-ietf-acme-tls-alpn-05#section-5.1
+var idPeAcmeIdentifierV1 = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 1, 31}
 
 type tlsALPNChallenge struct {
 	jws      *jws
@@ -58,7 +58,7 @@ func TLSALPNChallengeBlocks(domain, keyAuth string) ([]byte, []byte, error) {
 
 	// Add the keyAuth digest as the acmeValidation-v1 extension
 	// (marked as critical such that it won't be used by non-ACME software).
-	// Reference: https://tools.ietf.org/html/draft-ietf-acme-tls-alpn-01#section-3
+	// Reference: https://tools.ietf.org/html/draft-ietf-acme-tls-alpn-05#section-3
 	extensions := []pkix.Extension{
 		{
 			Id:       idPeAcmeIdentifierV1,