diff --git a/src/passes/6-transpiler/transpiler.ml b/src/passes/6-transpiler/transpiler.ml
index f1c61f7ba..11ff10988 100644
--- a/src/passes/6-transpiler/transpiler.ml
+++ b/src/passes/6-transpiler/transpiler.ml
@@ -407,6 +407,7 @@ and transpile_annotated_expression (ae:AST.annotated_expression) : expression re
       | ("LIST_MAP" , lst) -> map lst
       | ("MAP_MAP" , lst) -> map lst
       | ("LIST_FOLD" , lst) -> fold lst
+      | ("MAP_FOLD" , lst) -> fold lst
       | _ -> (
           let%bind lst' = bind_map_list (transpile_annotated_expression) lst in
           return @@ E_constant (name , lst')
diff --git a/src/passes/operators/operators.ml b/src/passes/operators/operators.ml
index 927d16c6c..9ead3b7bd 100644
--- a/src/passes/operators/operators.ml
+++ b/src/passes/operators/operators.ml
@@ -86,6 +86,7 @@ module Simplify = struct
       ("list_map" , "LIST_MAP") ;
       ("map_iter" , "MAP_ITER") ;
       ("map_map" , "MAP_MAP") ;
+      ("map_fold" , "MAP_FOLD") ;
       ("sha_256" , "SHA256") ;
       ("sha_512" , "SHA512") ;
       ("blake2b" , "BLAKE2b") ;
@@ -155,6 +156,7 @@ module Simplify = struct
       ("Map.remove" , "MAP_REMOVE") ;
       ("Map.iter" , "MAP_ITER") ;
       ("Map.map" , "MAP_MAP") ;
+      ("Map.fold" , "LIST_FOLD") ;
 
       ("String.length", "SIZE") ;
       ("String.size", "SIZE") ;
@@ -285,16 +287,6 @@ module Typer = struct
     let%bind () = assert_eq_1 arg (t_pair k v ()) in
     ok @@ t_map k res ()
 
-  let map_fold : typer = typer_2 "MAP_FOLD" @@ fun f m ->
-    let%bind (k, v) = get_t_map m in
-    let%bind (arg_1 , res) = get_t_function f in
-    let%bind (arg_2 , res') = get_t_function res in
-    let%bind (arg_3 , res'') = get_t_function res' in
-    let%bind () = assert_eq_1 arg_1 k in
-    let%bind () = assert_eq_1 arg_2 v in
-    let%bind () = assert_eq_1 arg_3 res'' in
-    ok @@ res'
-
   let size = typer_1 "SIZE" @@ fun t ->
     let%bind () =
       Assert.assert_true @@
@@ -504,6 +496,20 @@ module Typer = struct
     let%bind () = assert_eq_1 ~msg:"res init" res init in
     ok res
 
+  let map_fold = typer_3 "MAP_FOLD" @@ fun map init body ->
+    let%bind (arg , res) = get_t_function body in
+    let%bind (prec , cur) = get_t_pair arg in
+    let%bind (key , value) = get_t_map map in
+    let msg = Format.asprintf "%a vs %a"
+        Ast_typed.PP.type_value key
+        Ast_typed.PP.type_value arg
+    in
+    trace (simple_error ("bad list fold:" ^ msg)) @@
+    let%bind () = assert_eq_1 ~msg:"key cur" (t_pair key value ()) cur in
+    let%bind () = assert_eq_1 ~msg:"prec res" prec res in
+    let%bind () = assert_eq_1 ~msg:"res init" res init in
+    ok res
+
   let not_ = typer_1 "NOT" @@ fun elt ->
     if eq_1 elt (t_bool ())
     then ok @@ t_bool ()
diff --git a/src/test/contracts/map.ligo b/src/test/contracts/map.ligo
index af3697768..722412603 100644
--- a/src/test/contracts/map.ligo
+++ b/src/test/contracts/map.ligo
@@ -44,3 +44,7 @@ function iter_op (const m : foobar) : int is
 function map_op (const m : foobar) : foobar is
   function increment (const i : int ; const j : int) : int is block { skip } with j + 1 ;
   block { skip } with map_map(m , increment) ;
+
+function fold_op (const m : foobar) : int is
+  function aggregate (const i : int ; const j : (int * int)) : int is block { skip } with i + j.0 + j.1 ;
+  block { skip } with map_fold(m , 10 , aggregate)
diff --git a/src/test/integration_tests.ml b/src/test/integration_tests.ml
index 4e280647e..eab8395da 100644
--- a/src/test/integration_tests.ml
+++ b/src/test/integration_tests.ml
@@ -400,6 +400,11 @@ let map () : unit result =
     let expected = e_int 66 in
     expect_eq program "iter_op" input expected
   in
+  let%bind () =
+    let input = ez [(1 , 10) ; (2 , 20) ; (3 , 30) ] in
+    let expected = e_int 76 in
+    expect_eq program "fold_op" input expected
+  in
   let%bind () =
     let input = ez [(1 , 10) ; (2 , 20) ; (3 , 30) ] in
     let expected = ez [(1 , 11) ; (2 , 21) ; (3 , 31) ] in
@@ -676,19 +681,19 @@ let mligo_list () : unit result =
   let%bind program = mtype_file "./contracts/list.mligo" in
   let aux lst = e_list @@ List.map e_int lst in
   let%bind () = expect_eq program "fold_op" (aux [ 1 ; 2 ; 3 ]) (e_int 16) in
-  (* let%bind () =
-   *   let make_input n =
-   *     e_pair (e_list [e_int n; e_int (2*n)])
-   *       (e_pair (e_int 3) (e_list [e_int 8])) in
-   *   let make_expected n =
-   *     e_pair (e_typed_list [] t_operation)
-   *       (e_pair (e_int (n+3)) (e_list [e_int (2*n)]))
-   *   in
-   *   expect_eq_n program "main" make_input make_expected
-   * in
-   * let%bind () = expect_eq_evaluate program "x" (e_list []) in
-   * let%bind () = expect_eq_evaluate program "y" (e_list @@ List.map e_int [3 ; 4 ; 5]) in
-   * let%bind () = expect_eq_evaluate program "z" (e_list @@ List.map e_int [2 ; 3 ; 4 ; 5]) in *)
+  let%bind () =
+    let make_input n =
+      e_pair (e_list [e_int n; e_int (2*n)])
+        (e_pair (e_int 3) (e_list [e_int 8])) in
+    let make_expected n =
+      e_pair (e_typed_list [] t_operation)
+        (e_pair (e_int (n+3)) (e_list [e_int (2*n)]))
+    in
+    expect_eq_n program "main" make_input make_expected
+  in
+  let%bind () = expect_eq_evaluate program "x" (e_list []) in
+  let%bind () = expect_eq_evaluate program "y" (e_list @@ List.map e_int [3 ; 4 ; 5]) in
+  let%bind () = expect_eq_evaluate program "z" (e_list @@ List.map e_int [2 ; 3 ; 4 ; 5]) in
   ok ()
 
 let lambda_mligo () : unit result =