diff --git a/compiler/heptagon/transformations/last_mapfold.ml b/compiler/heptagon/transformations/last_mapfold.ml
new file mode 100644
index 0000000..b23fbd4
--- /dev/null
+++ b/compiler/heptagon/transformations/last_mapfold.ml
@@ -0,0 +1,60 @@
+(**************************************************************************)
+(*                                                                        *)
+(*  Heptagon                                                              *)
+(*                                                                        *)
+(*  Author : Marc Pouzet                                                  *)
+(*  Organization : Demons, LRI, University of Paris-Sud, Orsay            *)
+(*                                                                        *)
+(**************************************************************************)
+(* removing accessed to shared variables (last x)      *)
+open Heptagon
+open Hept_mapfold
+open Ident
+
+(* introduce a fresh equation [last_x = pre(x)] for every *)
+(* variable declared with a last *)
+let last (eq_list, env, v) { v_ident = n; v_type = t; v_last = last } =
+  match last with
+    | Var -> (eq_list, env, v)
+    | Last(default) ->
+        let lastn = Ident.fresh ("last" ^ (sourcename n)) in
+        let eq = mk_equation (Eeq (Evarpat lastn,
+                                   mk_exp (Epre (default,
+                                                 mk_exp (Evar n) t)) t)) in
+        eq:: eq_list,
+        Env.add n lastn env,
+        (mk_var_dec lastn t) :: v
+
+let extend_env env v = List.fold_left last ([], env, []) v
+
+let edesc funs env ed = match ed with
+  | Elast x ->
+      let lx = Env.find x env in Evar lx, env
+  | _ -> raise Misc.Fallback
+
+let block funs env b =
+  let eq_lastn_n_list, env, last_v = extend_env env b.b_local in
+  let b, _ = Hept_mapfold.block funs env b in
+    { b with b_local = b.b_local @ last_v;
+        b_equs = eq_lastn_n_list @ b.b_equs }, env
+
+let contract funs env contract =
+  let eq_lastn_n_list, env', last_v = extend_env env contract.c_local in
+  let contract, _ = Hept_mapfold.contract funs env contract in
+    { contract with c_local = contract.c_local @ last_v;
+        c_eq = eq_lastn_n_list @ contract.c_eq }, env
+
+let node_dec funs env n =
+  let _, env, _ = extend_env Env.empty n.n_input in
+  let eq_lasto_list, env, last_o = extend_env env n.n_output in
+  let eq_lastn_n_list, env, last_v = extend_env env n.n_local in
+  let n, _  = Hept_mapfold.node_dec funs env n in
+    { n with n_local = n.n_local @ last_o @ last_v;
+        n_equs = eq_lasto_list @ eq_lastn_n_list @ n.n_equs }, env
+
+let program p =
+  let funs = { Hept_mapfold.defaults with
+                 node_dec = node_dec; block = block;
+                 contract = contract; edesc = edesc } in
+  let p, _ = Hept_mapfold.program_it funs Env.empty p in
+    p