diff --git a/src/API.mli b/src/API.mli
index 835b453ef..3b5c58d3f 100644
--- a/src/API.mli
+++ b/src/API.mli
@@ -1271,6 +1271,8 @@ module Utils : sig
     module type S = sig
       include Map.S
       include Show1 with type 'a t := 'a t
+      val pp_key : Format.formatter -> key -> unit
+      val show_key : key -> string
     end
 
     module type OrderedType = sig
diff --git a/src/utils/util.ml b/src/utils/util.ml
index 62e184b02..7eb6223a1 100644
--- a/src/utils/util.ml
+++ b/src/utils/util.ml
@@ -25,6 +25,8 @@ module Map = struct
   module type S = sig
     include Map.S
     include Show1 with type 'a t := 'a t
+    val pp_key : Format.formatter -> key -> unit
+    val show_key : key -> string
   end
 
   module type OrderedType = sig
@@ -44,6 +46,9 @@ module Map = struct
       pp f fmt m;
       Format.fprintf fmt "@?";
       Buffer.contents b
+
+    let pp_key = Ord.pp
+    let show_key = Ord.show 
   end
 
 end
diff --git a/src/utils/util.mli b/src/utils/util.mli
index 20245d687..cc18f0837 100644
--- a/src/utils/util.mli
+++ b/src/utils/util.mli
@@ -27,6 +27,8 @@ module Map : sig
   module type S = sig
     include Map.S
     include Show1 with type 'a t := 'a t
+    val pp_key : Format.formatter -> key -> unit
+    val show_key : key -> string
   end
 
   module type OrderedType = sig