diff --git a/dnsapi.md b/dnsapi.md
index 25e0117..4f82768 100644
--- a/dnsapi.md
+++ b/dnsapi.md
@@ -916,10 +916,14 @@ ACME DNS is a limited DNS server with RESTful HTTP API to handle ACME DNS challe
 https://github.com/joohoi/acme-dns
 
 ```
-export ACMEDNS_UPDATE_URL="https://auth.acme-dns.io/update"
-export ACMEDNS_USERNAME="<username>"
-export ACMEDNS_PASSWORD="<password>"
-export ACMEDNS_SUBDOMAIN="<subdomain>"
+# Usage:
+# export ACMEDNS_BASE_URL="https://auth.acme-dns.io"
+#
+# You can optionally define an already existing account:
+#
+# export ACMEDNS_USERNAME="<username>"
+# export ACMEDNS_PASSWORD="<password>"
+# export ACMEDNS_SUBDOMAIN="<subdomain>"
 
 acme.sh --issue --dns dns_acmedns -d example.com -d www.example.com
 ```