diff --git a/src/threads/CCPool.mli b/src/threads/CCPool.mli
index 93a543b4..a27e7838 100644
--- a/src/threads/CCPool.mli
+++ b/src/threads/CCPool.mli
@@ -14,8 +14,10 @@ end
 
 exception Stopped
 
+[@@@ocaml.warning "-67"]
+
 (** {2 Create a new Pool} *)
-module Make (_ : PARAM) : sig
+module Make (P : PARAM) : sig
   val run : (unit -> _) -> unit
   (** [run f] schedules [f] for being executed in the thread pool. *)