diff --git a/string/levenshtein.ml b/string/levenshtein.ml
index 7ce560a2..9aec05c8 100644
--- a/string/levenshtein.ml
+++ b/string/levenshtein.ml
@@ -167,7 +167,7 @@ module Make(Str : STRING) = struct
       | Epsilon of int * int
 
     (* non deterministic automaton *)
-    type t = transition list array array
+    type _t = transition list array array
 
     let length nda = Array.length nda
 
@@ -278,7 +278,7 @@ module Make(Str : STRING) = struct
       let compare = Pervasives.compare
     end)
 
-    let set_to_string s =
+    let _set_to_string s =
       let b = Buffer.create 15 in
       Buffer.add_char b '{';
       NDAStateSet.iter
@@ -470,12 +470,6 @@ module Make(Str : STRING) = struct
   let of_list ~limit l =
     of_string ~limit (Str.of_list l)
 
-  type match_result =
-    | TooFar
-    | Distance of int
-
-  exception FoundDistance of int
-
   let rec __find_char c l = match l with
     | [] -> raise Not_found
     | (c', next) :: l' ->