diff --git a/src/core/CCFormat.ml b/src/core/CCFormat.ml
index 9dd8037c..3afcf352 100644
--- a/src/core/CCFormat.ml
+++ b/src/core/CCFormat.ml
@@ -32,7 +32,6 @@ let newline = Format.pp_force_newline
 let substring out (s, i, len) : unit = string out (String.sub s i len)
 let text = Format.pp_print_text
 let option = Format.pp_print_option
-let opt = option
 let result = Format.pp_print_result
 
 let string_lines out (s : string) : unit =
@@ -91,6 +90,11 @@ let iter ?(sep = return ",@ ") pp fmt seq =
         sep fmt ();
       pp fmt x)
 
+let opt pp fmt x =
+  match x with
+  | None -> Format.pp_print_string fmt "none"
+  | Some x -> Format.fprintf fmt "some %a" pp x
+
 let pair ?(sep = return ",@ ") ppa ppb fmt (a, b) =
   Format.fprintf fmt "%a%a%a" ppa a sep () ppb b
 
diff --git a/src/core/CCFormat.mli b/src/core/CCFormat.mli
index 12b1ca81..ec225687 100644
--- a/src/core/CCFormat.mli
+++ b/src/core/CCFormat.mli
@@ -100,13 +100,16 @@ val seq : ?sep:unit printer -> 'a printer -> 'a Seq.t printer
 val iter : ?sep:unit printer -> 'a printer -> 'a iter printer
 
 val option : ?none:unit printer -> 'a printer -> 'a option printer
-(** [opt ?none pp] prints options as follows:
+(** [option ?none pp] prints options as follows:
         - [Some x] will become [pp x]
         - [None] will become [none ()]
+    Alias of {!Format.pp_print_option}
     @since NEXT_RELEASE *)
 
-val opt : ?none:unit printer -> 'a printer -> 'a option printer
-(** Alias of {!option} *)
+val opt : 'a printer -> 'a option printer
+(** [opt pp] prints options as follows:
+    - [Some x] will become "some foo" if [pp x ---> "foo"].
+    - [None] will become "none". *)
 
 val result : ok:'a printer -> error:'e printer -> ('a, 'e) result printer