diff -r -u frama-c-Nitrogen-20111001.orig/src/type/datatype.mli frama-c-Nitrogen-20111001/src/type/datatype.mli
--- frama-c-Nitrogen-20111001.orig/src/type/datatype.mli	2011-10-10 10:38:09.000000000 +0200
+++ frama-c-Nitrogen-20111001/src/type/datatype.mli	2012-01-05 18:35:45.000000000 +0100
@@ -249,10 +249,27 @@
 
 end
 
+module type Hashtbl_S = sig
+    type key
+    type 'a t
+    val create : int -> 'a t
+    val clear : 'a t -> unit
+    val copy : 'a t -> 'a t
+    val add : 'a t -> key -> 'a -> unit
+    val remove : 'a t -> key -> unit
+    val find : 'a t -> key -> 'a
+    val find_all : 'a t -> key -> 'a list
+    val replace : 'a t -> key -> 'a -> unit
+    val mem : 'a t -> key -> bool
+    val iter : (key -> 'a -> unit) -> 'a t -> unit
+    val fold : (key -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b
+    val length : 'a t -> int
+end
+
 (** A standard OCaml hashtbl signature extended with datatype operations. *)
 module type Hashtbl = sig
 
-  include Hashtbl.S
+  include Hashtbl_S
 
   val memo: 'a t -> key -> (key -> 'a) -> 'a
   (** [memo tbl k f] returns the binding of [k] in [tbl]. If there is
@@ -468,7 +485,7 @@
 module Map(M: Map_common_interface.S)(Key: S with type t = M.key)(Info: Functor_info) :
   Map with type 'a t = 'a M.t and type key = M.key and module Key = Key
 
-module Hashtbl(H: Hashtbl.S)(Key: S with type t = H.key)(Info : Functor_info):
+module Hashtbl(H: Hashtbl_S)(Key: S with type t = H.key)(Info : Functor_info):
   Hashtbl with type 'a t = 'a H.t and type key = H.key and module Key = Key
 
 module type Sub_caml_weak_hashtbl = sig
diff -r -u frama-c-Nitrogen-20111001.orig/src/wp/LogicId.mli frama-c-Nitrogen-20111001/src/wp/LogicId.mli
--- frama-c-Nitrogen-20111001.orig/src/wp/LogicId.mli	2011-10-10 10:38:21.000000000 +0200
+++ frama-c-Nitrogen-20111001/src/wp/LogicId.mli	2012-01-05 18:38:36.000000000 +0100
@@ -40,7 +40,7 @@
 
 module Iset : Set.S with type elt = t
 module Imap : Map.S with type key = t
-module Ihmap : Hashtbl.S with type key = t
+module Ihmap : Datatype.Hashtbl_S with type key = t
 
 (** {3 Name Spaces} *)
 
diff -r -u frama-c-Nitrogen-20111001.orig/src/wp/fol_formula.ml frama-c-Nitrogen-20111001/src/wp/fol_formula.ml
--- frama-c-Nitrogen-20111001.orig/src/wp/fol_formula.ml	2011-10-10 10:38:21.000000000 +0200
+++ frama-c-Nitrogen-20111001/src/wp/fol_formula.ml	2012-01-05 18:31:40.000000000 +0100
@@ -389,7 +389,7 @@
 module type Identifiable =
 sig
   type t
-  module H : Hashtbl.S
+  module H : Datatype.Hashtbl_S
   val index : t -> H.key
   val prefix : string
   val basename : t -> string
diff -r -u frama-c-Nitrogen-20111001.orig/src/wp/formula.mli frama-c-Nitrogen-20111001/src/wp/formula.mli
--- frama-c-Nitrogen-20111001.orig/src/wp/formula.mli	2011-10-10 10:38:21.000000000 +0200
+++ frama-c-Nitrogen-20111001/src/wp/formula.mli	2012-01-05 18:38:28.000000000 +0100
@@ -147,7 +147,7 @@
   module type Identifiable =
   sig
     type t
-    module H : Hashtbl.S
+    module H : Datatype.Hashtbl_S
     val index : t -> H.key
     val prefix : string
     val basename : t -> string
--- frama-c-Nitrogen-20111001.orig/src/type/datatype.ml	2011-10-10 10:38:09.000000000 +0200
+++ frama-c-Nitrogen-20111001/src/type/datatype.ml	2012-01-05 18:46:38.000000000 +0100
@@ -306,8 +306,26 @@
   module Make(Data: S) : S with type t = Data.t t
 end
 
+module type Hashtbl_S =
+  sig
+    type key
+    type 'a t
+    val create : int -> 'a t
+    val clear : 'a t -> unit
+    val copy : 'a t -> 'a t
+    val add : 'a t -> key -> 'a -> unit
+    val remove : 'a t -> key -> unit
+    val find : 'a t -> key -> 'a
+    val find_all : 'a t -> key -> 'a list
+    val replace : 'a t -> key -> 'a -> unit
+    val mem : 'a t -> key -> bool
+    val iter : (key -> 'a -> unit) -> 'a t -> unit
+    val fold : (key -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b
+    val length : 'a t -> int
+  end
+
 module type Hashtbl = sig
-  include Hashtbl.S
+  include Hashtbl_S
   val memo: 'a t -> key -> (key -> 'a) -> 'a
   module Key: S with type t = key
   module Make(Data: S) : S with type t = Data.t t
@@ -970,7 +988,7 @@
 module Initial_caml_hashtbl = Hashtbl
 
 (* ocaml functors are generative *)
-module Hashtbl(H: Hashtbl.S)(Key: S with type t = H.key)(Info : Functor_info) =
+module Hashtbl(H: Hashtbl_S)(Key: S with type t = H.key)(Info : Functor_info) =
 struct
 
   let () = check Key.equal "equal" Key.name Info.module_name
--- frama-c-Nitrogen-20111001/configure.orig	2012-03-12 16:14:45.000000000 +0100
+++ frama-c-Nitrogen-20111001/configure	2012-03-12 16:15:06.000000000 +0100
@@ -2675,6 +2675,7 @@
          ;;
   3.10*) echo "${ECHO_T}good!";;
   3.1*) echo "${ECHO_T}good!"; OCAML_ANNOT_OPTION="-annot";;
+  4.0*) echo "${ECHO_T}good!"; OCAML_ANNOT_OPTION="-annot";;
   *) echo "${ECHO_T}Incompatible version!"; exit 2;;
 esac