diff --git a/acme/challenge.go b/acme/challenge.go
index b880708c..c3f8dde8 100644
--- a/acme/challenge.go
+++ b/acme/challenge.go
@@ -26,8 +26,11 @@ import (
 type ChallengeType string
 
 const (
-	HTTP01    ChallengeType = "http-01"
-	DNS01     ChallengeType = "dns-01"
+	// HTTP01 is the http-01 ACME challenge type
+	HTTP01 ChallengeType = "http-01"
+	// DNS01 is the dns-01 ACME challenge type
+	DNS01 ChallengeType = "dns-01"
+	// TLSALPN01 is the tls-alpn-01 ACME challenge type
 	TLSALPN01 ChallengeType = "tls-alpn-01"
 )
 
diff --git a/acme/order.go b/acme/order.go
index 237c6979..bd820da1 100644
--- a/acme/order.go
+++ b/acme/order.go
@@ -17,7 +17,9 @@ import (
 type IdentifierType string
 
 const (
-	IP  IdentifierType = "ip"
+	// IP is the ACME ip identifier type
+	IP IdentifierType = "ip"
+	// DNS is the ACME dns identifier type
 	DNS IdentifierType = "dns"
 )