diff --git a/src/ocserv-args.def b/src/ocserv-args.def
index 74edee0d..ba8de49b 100644
--- a/src/ocserv-args.def
+++ b/src/ocserv-args.def
@@ -96,6 +96,8 @@ server-key = /path/to/key.pem
 
 # The object identifier that will be used to read the user ID in the client certificate.
 # The object identifier should be part of the certificate's DN
+# Useful OIDs are: 
+#  CN = 2.5.4.3, UID = 0.9.2342.19200300.100.1.1
 #cert-user-oid = 0.9.2342.19200300.100.1.1
 
 # A revocation list of ca-cert is set