diff --git a/src/compiler/gencode/translate.ml b/src/compiler/gencode/translate.ml
index d6b4cdbe..c26201e2 100644
--- a/src/compiler/gencode/translate.ml
+++ b/src/compiler/gencode/translate.ml
@@ -458,10 +458,11 @@ let rec exp env loop_path code { Zelus.e_desc = desc } =
      Econcat { left = e1; left_size = s1; right = e2; right_size = s2 }, code
   | Zelus.Eop(Zelus.Eatomic, [e]) ->
      exp env loop_path code e  
-  | Zelus.Elet _ | Zelus.Eop(Eseq, _) | Zelus.Eop(Eperiod, _) 
-  | Zelus.Eop _ | Zelus.Epresent _
-  | Zelus.Ematch _ | Zelus.Elocal _ -> assert false
-  | Zelus.Eapp { f; arg_list } ->
+  | Zelus.Eop(Eseq, [e1; e2]) ->
+     let e1, code  = exp env loop_path code e1 in
+     let e2, code = exp env loop_path code e2 in
+     Oaux.seq e1 e2, code
+   | Zelus.Eapp { f; arg_list } ->
      (* make an application *)
      let make_app f arg_list =
        match arg_list with | [] -> f | _ -> Eapp { f; arg_list } in
@@ -490,7 +491,10 @@ let rec exp env loop_path code { Zelus.e_desc = desc } =
   | Eforloop _ -> Misc.not_yet_implemented "for loops"
   | Ereset _ -> Misc.not_yet_implemented "reset"
   | Eassert _ -> Misc.not_yet_implemented "assert"
-     
+  | Zelus.Elet _
+    | Zelus.Eop(Eperiod, _)  | Zelus.Eop _ | Zelus.Epresent _
+  | Zelus.Ematch _ | Zelus.Elocal _ -> assert false
+ 
 and arg a_list =
   match a_list with | [] -> Ewildpat | _ -> Etuplepat (List.map vardec a_list)
 
diff --git a/src/compiler/rewrite/deadcode.ml b/src/compiler/rewrite/deadcode.ml
index d640edb3..26a711f3 100644
--- a/src/compiler/rewrite/deadcode.ml
+++ b/src/compiler/rewrite/deadcode.ml
@@ -164,7 +164,7 @@ let pattern funs useful ({ pat_desc } as p) =
   | Evarpat(x) ->
      if S.mem x useful then p, useful else { p with pat_desc = Ewildpat }, useful
   | Ealiaspat(p_alias, x) ->
-     let p_alias, acc = Mapfold.pattern funs useful p_alias in
+     let p_alias, acc = Mapfold.pattern_it funs useful p_alias in
      if S.mem x useful then { p with pat_desc = Ealiaspat(p_alias, x) }, useful
      else p_alias, useful
   | _ -> raise Mapfold.Fallback
@@ -172,7 +172,7 @@ let pattern funs useful ({ pat_desc } as p) =
 (* Remove useless equations. [useful] is the set of useful names *)
 let equation funs useful eq =
   let eq_empty = Aux.eqmake Defnames.empty EQempty in
-  let { eq_desc; eq_write } as eq, useful = Mapfold.equation_it funs useful eq in
+  let { eq_desc; eq_write } as eq, useful = Mapfold.equation funs useful eq in
   match eq_desc with
   | EQeq(p, e) ->
      let { v = w } = Vars.pattern { lv = S.empty; v = S.empty } p in
@@ -221,7 +221,7 @@ let remove_useless_in_equation useful eq =
 
 (* the main entry for expressions. Warning: [e] must be in normal form *)
 let expression funs acc e =
-  let { e_desc } as e, acc = Mapfold.expression_it funs acc e in
+  let { e_desc } as e, acc = Mapfold.expression funs acc e in
   match e_desc with
   | Elet({ l_eq } as l, e_let) ->
      let { v } = Vars.expression { lv = S.empty; v = S.empty } e_let in