diff --git a/src/core/CCOpt.ml b/src/core/CCOpt.ml
index 10974bf5..7527077a 100644
--- a/src/core/CCOpt.ml
+++ b/src/core/CCOpt.ml
@@ -114,6 +114,11 @@ let get_exn_or msg = function
   | Some x -> x
   | None -> invalid_arg msg
 
+(*$T
+  (try get_exn_or "ohno" (None:unit option); false with Invalid_argument s->s= "ohno")
+  123 = get_exn_or "yes" (Some 123)
+*)
+
 let get_lazy default_fn x = match x with
   | None -> default_fn ()
   | Some y -> y
diff --git a/src/core/CCOpt.mli b/src/core/CCOpt.mli
index 98992cf8..64f4b527 100644
--- a/src/core/CCOpt.mli
+++ b/src/core/CCOpt.mli
@@ -95,8 +95,10 @@ val get_exn : 'a t -> 'a
 *)
 
 val get_exn_or : string -> 'a t -> 'a
-(** [get_exn msg o] returns [x] if [o] is [Some x] or fails with [Invalid_argument msg] if [o] is [None].
-    @raise Invalid_argument if the option is [None]. *)
+(** [get_exn_or msg o] returns [x] if [o] is [Some x]
+    or fails with [Invalid_argument msg] if [o] is [None].
+    @raise Invalid_argument if the option is [None].
+    @since NEXT_RELEASE *)
 
 val get_lazy : (unit -> 'a) -> 'a t -> 'a
 (** [get_lazy default_fn o] unwraps [o], but if [o] is [None] it returns [default_fn ()] instead.