diff --git a/lib/hx509/hxtool-commands.in b/lib/hx509/hxtool-commands.in
index 6150355be..1b67bbee6 100644
--- a/lib/hx509/hxtool-commands.in
+++ b/lib/hx509/hxtool-commands.in
@@ -540,6 +540,11 @@ command = {
 		type = "string"
 		help = "PK-INIT principal (for SAN)"
 	}
+	option = {
+		long = "ms-upn"
+		type = "string"
+		help = "Microsoft UPN (for SAN)"
+	}
 	option = {
 		long = "jid"
 		type = "string"