diff --git a/ocaml/MO_label.mli b/ocaml/MO_label.mli
index 732bf1f2..dd4bb7bd 100644
--- a/ocaml/MO_label.mli
+++ b/ocaml/MO_label.mli
@@ -4,6 +4,7 @@ type t =
   | Natural
   | Localized
   | Orthonormalized
+  | MCSCF
   | None
 [@@deriving sexp]