diff --git a/src/proto_alpha/lib_protocol/TEZOS_PROTOCOL b/src/proto_alpha/lib_protocol/TEZOS_PROTOCOL
index f658ff5063aa50b21359ac1aec83bec56fcccb49..38e90299cc53996e58f3685e7a1a38ffdf1254e3 100644
--- a/src/proto_alpha/lib_protocol/TEZOS_PROTOCOL
+++ b/src/proto_alpha/lib_protocol/TEZOS_PROTOCOL
@@ -91,11 +91,11 @@
 
         "Local_gas_counter",
         "Script_tc_errors",
+        "Script_ir_annot",
         "Script_typed_ir",
         "Script_typed_ir_size",
         "Script_typed_ir_size_costs",
         "Michelson_v1_gas",
-        "Script_ir_annot",
         "Script_list",
         "Script_comparable",
         "Script_set",
diff --git a/src/proto_alpha/lib_protocol/dune.inc b/src/proto_alpha/lib_protocol/dune.inc
index ee3cdd15b35d397b46b0d4cf5bc656db08422565..3e63ce628659b6b32e6cc86128f98dd23104b278 100644
--- a/src/proto_alpha/lib_protocol/dune.inc
+++ b/src/proto_alpha/lib_protocol/dune.inc
@@ -111,11 +111,11 @@ module CamlinternalFormatBasics = struct include CamlinternalFormatBasics end
    alpha_context.mli alpha_context.ml
    local_gas_counter.ml
    script_tc_errors.ml
+   script_ir_annot.mli script_ir_annot.ml
    script_typed_ir.mli script_typed_ir.ml
    script_typed_ir_size.mli script_typed_ir_size.ml
    script_typed_ir_size_costs.mli script_typed_ir_size_costs.ml
    michelson_v1_gas.mli michelson_v1_gas.ml
-   script_ir_annot.mli script_ir_annot.ml
    script_list.mli script_list.ml
    script_comparable.mli script_comparable.ml
    script_set.mli script_set.ml
@@ -231,11 +231,11 @@ module CamlinternalFormatBasics = struct include CamlinternalFormatBasics end
    alpha_context.mli alpha_context.ml
    local_gas_counter.ml
    script_tc_errors.ml
+   script_ir_annot.mli script_ir_annot.ml
    script_typed_ir.mli script_typed_ir.ml
    script_typed_ir_size.mli script_typed_ir_size.ml
    script_typed_ir_size_costs.mli script_typed_ir_size_costs.ml
    michelson_v1_gas.mli michelson_v1_gas.ml
-   script_ir_annot.mli script_ir_annot.ml
    script_list.mli script_list.ml
    script_comparable.mli script_comparable.ml
    script_set.mli script_set.ml
@@ -351,11 +351,11 @@ module CamlinternalFormatBasics = struct include CamlinternalFormatBasics end
    alpha_context.mli alpha_context.ml
    local_gas_counter.ml
    script_tc_errors.ml
+   script_ir_annot.mli script_ir_annot.ml
    script_typed_ir.mli script_typed_ir.ml
    script_typed_ir_size.mli script_typed_ir_size.ml
    script_typed_ir_size_costs.mli script_typed_ir_size_costs.ml
    michelson_v1_gas.mli michelson_v1_gas.ml
-   script_ir_annot.mli script_ir_annot.ml
    script_list.mli script_list.ml
    script_comparable.mli script_comparable.ml
    script_set.mli script_set.ml
@@ -493,11 +493,11 @@ include Tezos_raw_protocol_alpha.Main
    Alpha_context
    Local_gas_counter
    Script_tc_errors
+   Script_ir_annot
    Script_typed_ir
    Script_typed_ir_size
    Script_typed_ir_size_costs
    Michelson_v1_gas
-   Script_ir_annot
    Script_list
    Script_comparable
    Script_set
@@ -654,11 +654,11 @@ include Tezos_raw_protocol_alpha.Main
    alpha_context.mli alpha_context.ml
    local_gas_counter.ml
    script_tc_errors.ml
+   script_ir_annot.mli script_ir_annot.ml
    script_typed_ir.mli script_typed_ir.ml
    script_typed_ir_size.mli script_typed_ir_size.ml
    script_typed_ir_size_costs.mli script_typed_ir_size_costs.ml
    michelson_v1_gas.mli michelson_v1_gas.ml
-   script_ir_annot.mli script_ir_annot.ml
    script_list.mli script_list.ml
    script_comparable.mli script_comparable.ml
    script_set.mli script_set.ml
diff --git a/src/proto_alpha/lib_protocol/script_ir_annot.ml b/src/proto_alpha/lib_protocol/script_ir_annot.ml
index 1c3436c23525dd246161a94d9be39941ad3867cf..9b1f60dbe4040e447d0fb3e40a6864849f61a3c9 100644
--- a/src/proto_alpha/lib_protocol/script_ir_annot.ml
+++ b/src/proto_alpha/lib_protocol/script_ir_annot.ml
@@ -26,7 +26,20 @@
 open Alpha_context
 open Micheline
 open Script_tc_errors
-open Script_typed_ir
+
+type var_annot = Var_annot of string [@@ocaml.unboxed]
+
+type type_annot = Type_annot of string [@@ocaml.unboxed]
+
+type field_annot = Field_annot of string [@@ocaml.unboxed]
+
+module FOR_TESTS = struct
+  let unsafe_var_annot_of_string s = Var_annot s
+
+  let unsafe_type_annot_of_string s = Type_annot s
+
+  let unsafe_field_annot_of_string s = Field_annot s
+end
 
 let default_now_annot = Some (Var_annot "now")
 
@@ -44,6 +57,8 @@ let default_self_annot = Some (Var_annot "self")
 
 let default_arg_annot = Some (Var_annot "arg")
 
+let lambda_arg_annot = Some (Var_annot "@arg")
+
 let default_param_annot = Some (Var_annot "parameter")
 
 let default_storage_annot = Some (Var_annot "storage")
diff --git a/src/proto_alpha/lib_protocol/script_ir_annot.mli b/src/proto_alpha/lib_protocol/script_ir_annot.mli
index 9a9008de146929a66acfa76c7244c175edb7aca3..d8b4f660fe76b2efe07c4501a583e7ee68707f35 100644
--- a/src/proto_alpha/lib_protocol/script_ir_annot.mli
+++ b/src/proto_alpha/lib_protocol/script_ir_annot.mli
@@ -24,7 +24,20 @@
 (*****************************************************************************)
 
 open Alpha_context
-open Script_typed_ir
+
+type var_annot = private Var_annot of string [@@ocaml.unboxed]
+
+type type_annot = private Type_annot of string [@@ocaml.unboxed]
+
+type field_annot = private Field_annot of string [@@ocaml.unboxed]
+
+module FOR_TESTS : sig
+  val unsafe_var_annot_of_string : string -> var_annot
+
+  val unsafe_type_annot_of_string : string -> type_annot
+
+  val unsafe_field_annot_of_string : string -> field_annot
+end
 
 (** Default annotations *)
 
@@ -44,6 +57,8 @@ val default_self_annot : var_annot option
 
 val default_arg_annot : var_annot option
 
+val lambda_arg_annot : var_annot option
+
 val default_param_annot : var_annot option
 
 val default_storage_annot : var_annot option
diff --git a/src/proto_alpha/lib_protocol/script_ir_translator.ml b/src/proto_alpha/lib_protocol/script_ir_translator.ml
index 992d1c3fb7033ca803d5f59a24accbaef0d2d0c3..2e7aa4efd3be2840b2a9406f8e9cd138e960375f 100644
--- a/src/proto_alpha/lib_protocol/script_ir_translator.ml
+++ b/src/proto_alpha/lib_protocol/script_ir_translator.ml
@@ -2724,7 +2724,7 @@ let[@coq_axiom_with_reason "gadt"] rec parse_data :
            ~stack_depth:(stack_depth + 1)
            ctxt
            ~legacy
-           (ta, Some (Var_annot "@arg"))
+           (ta, lambda_arg_annot)
            tr
            script_instr
   | (Lambda_t _, expr) ->
diff --git a/src/proto_alpha/lib_protocol/script_ir_translator.mli b/src/proto_alpha/lib_protocol/script_ir_translator.mli
index 031ff5561bd15788184a3b35acdf3f40978640f3..a2f8ce6037e95ca3c7c8ab4d2189ecd005939f2c 100644
--- a/src/proto_alpha/lib_protocol/script_ir_translator.mli
+++ b/src/proto_alpha/lib_protocol/script_ir_translator.mli
@@ -80,7 +80,7 @@ type toplevel = {
   arg_type : Script.node;
   storage_type : Script.node;
   views : Script_typed_ir.view Script_typed_ir.SMap.t;
-  root_name : Script_typed_ir.field_annot option;
+  root_name : Script_ir_annot.field_annot option;
 }
 
 type ('arg, 'storage) code = {
@@ -93,7 +93,7 @@ type ('arg, 'storage) code = {
   arg_type : 'arg Script_typed_ir.ty;
   storage_type : 'storage Script_typed_ir.ty;
   views : Script_typed_ir.view Script_typed_ir.SMap.t;
-  root_name : Script_typed_ir.field_annot option;
+  root_name : Script_ir_annot.field_annot option;
   code_size : Cache_memory_helpers.sint;
       (** This is an over-approximation of the value size in memory, in
          bytes, of the contract's static part, that is its source
@@ -130,7 +130,7 @@ type tc_context =
   | Toplevel : {
       storage_type : 'sto Script_typed_ir.ty;
       param_type : 'param Script_typed_ir.ty;
-      root_name : Script_typed_ir.field_annot option;
+      root_name : Script_ir_annot.field_annot option;
     }
       -> tc_context
 
@@ -395,8 +395,8 @@ val parse_toplevel :
   context -> legacy:bool -> Script.expr -> (toplevel * context) tzresult Lwt.t
 
 val add_field_annot :
-  Script_typed_ir.field_annot option ->
-  Script_typed_ir.var_annot option ->
+  Script_ir_annot.field_annot option ->
+  Script_ir_annot.var_annot option ->
   ('loc, 'prim) Micheline.node ->
   ('loc, 'prim) Micheline.node
 
@@ -456,7 +456,7 @@ val parse_contract_for_script :
 
 val find_entrypoint :
   't Script_typed_ir.ty ->
-  root_name:Script_typed_ir.field_annot option ->
+  root_name:Script_ir_annot.field_annot option ->
   string ->
   ((Script.node -> Script.node) * ex_ty) tzresult
 
@@ -465,7 +465,7 @@ module Entrypoints_map : Map.S with type key = string
 val list_entrypoints :
   't Script_typed_ir.ty ->
   context ->
-  root_name:Script_typed_ir.field_annot option ->
+  root_name:Script_ir_annot.field_annot option ->
   (Michelson_v1_primitives.prim list list
   * (Michelson_v1_primitives.prim list * Script.unlocated_michelson_node)
     Entrypoints_map.t)
diff --git a/src/proto_alpha/lib_protocol/script_typed_ir.ml b/src/proto_alpha/lib_protocol/script_typed_ir.ml
index 26f17381f716247486cb9bd3e207a76087ab2af4..ff42b060a85e7a10d341e269f4da3094f521b36e 100644
--- a/src/proto_alpha/lib_protocol/script_typed_ir.ml
+++ b/src/proto_alpha/lib_protocol/script_typed_ir.ml
@@ -26,6 +26,7 @@
 
 open Alpha_context
 open Script_int
+open Script_ir_annot
 
 (*
 
@@ -58,12 +59,6 @@ type step_constants = {
 
 (* Preliminary definitions. *)
 
-type var_annot = Var_annot of string [@@ocaml.unboxed]
-
-type type_annot = Type_annot of string [@@ocaml.unboxed]
-
-type field_annot = Field_annot of string [@@ocaml.unboxed]
-
 type never = |
 
 type address = Contract.t * string
diff --git a/src/proto_alpha/lib_protocol/script_typed_ir.mli b/src/proto_alpha/lib_protocol/script_typed_ir.mli
index 40210da778086e0efeb45f3dcc3d71780d31d387..382fa8b38c28450444319034279ab18ed3402fff 100644
--- a/src/proto_alpha/lib_protocol/script_typed_ir.mli
+++ b/src/proto_alpha/lib_protocol/script_typed_ir.mli
@@ -26,6 +26,7 @@
 
 open Alpha_context
 open Script_int
+open Script_ir_annot
 
 type step_constants = {
   source : Contract.t;
@@ -39,12 +40,6 @@ type step_constants = {
 
 (* Preliminary definitions. *)
 
-type var_annot = Var_annot of string [@@ocaml.unboxed]
-
-type type_annot = Type_annot of string [@@ocaml.unboxed]
-
-type field_annot = Field_annot of string [@@ocaml.unboxed]
-
 type never = |
 
 type address = Contract.t * string
diff --git a/src/proto_alpha/lib_protocol/script_typed_ir_size.ml b/src/proto_alpha/lib_protocol/script_typed_ir_size.ml
index 714eb18d8f2ded32693cab7e6969c065d951b6d6..a45aa36fcf00256ad4d29a4a5e46255c95a27785 100644
--- a/src/proto_alpha/lib_protocol/script_typed_ir_size.ml
+++ b/src/proto_alpha/lib_protocol/script_typed_ir_size.ml
@@ -33,11 +33,11 @@ let script_string_size s = Script_string.to_string s |> string_size
    Micheline representation and that the strings are always
    shared. (One can check that they are never copied.) Besides, the
    following types are unboxed so that they have no tags. *)
-let type_annot_size (Type_annot _) = !!0
+let type_annot_size (Script_ir_annot.Type_annot _) = !!0
 
-let field_annot_size (Field_annot _) = !!0
+let field_annot_size (Script_ir_annot.Field_annot _) = !!0
 
-let var_annot_size (Var_annot _) = !!0
+let var_annot_size (Script_ir_annot.Var_annot _) = !!0
 
 (* Memo-sizes are 16-bit integers *)
 let sapling_memo_size_size = !!0
diff --git a/src/proto_alpha/lib_protocol/test/test_typechecking.ml b/src/proto_alpha/lib_protocol/test/test_typechecking.ml
index 3c043cebc776a15eee918f71b419027650574ed9..57848a7e8ada208a79b800f9ee5bb30f26eade3c 100644
--- a/src/proto_alpha/lib_protocol/test/test_typechecking.ml
+++ b/src/proto_alpha/lib_protocol/test/test_typechecking.ml
@@ -208,6 +208,12 @@ let test_parse_ty ctxt node expected =
       Script_ir_translator.ty_eq ctxt (location node) actual expected
       >|? fun (_, ctxt) -> ctxt )
 
+let var_annot = Script_ir_annot.FOR_TESTS.unsafe_var_annot_of_string
+
+let type_annot = Script_ir_annot.FOR_TESTS.unsafe_type_annot_of_string
+
+let field_annot = Script_ir_annot.FOR_TESTS.unsafe_field_annot_of_string
+
 let test_parse_comb_type () =
   let open Script in
   let open Script_typed_ir in
@@ -250,7 +256,7 @@ let test_parse_comb_type () =
   (* pair (nat %a) nat *)
   pair_t
     (-1)
-    (nat_ty, Some (Field_annot "a"), None)
+    (nat_ty, Some (field_annot "a"), None)
     (nat_ty, None, None)
     ~annot:None
   >>??= fun pair_nat_a_nat_ty ->
@@ -260,7 +266,7 @@ let test_parse_comb_type () =
   pair_t
     (-1)
     (nat_ty, None, None)
-    (nat_ty, Some (Field_annot "b"), None)
+    (nat_ty, Some (field_annot "b"), None)
     ~annot:None
   >>??= fun pair_nat_nat_b_ty ->
   test_parse_ty ctxt (pair_prim2 nat_prim nat_prim_b) pair_nat_nat_b_ty
@@ -268,8 +274,8 @@ let test_parse_comb_type () =
   (* pair (nat %a) (nat %b) *)
   pair_t
     (-1)
-    (nat_ty, Some (Field_annot "a"), None)
-    (nat_ty, Some (Field_annot "b"), None)
+    (nat_ty, Some (field_annot "a"), None)
+    (nat_ty, Some (field_annot "b"), None)
     ~annot:None
   >>??= fun pair_nat_a_nat_b_ty ->
   test_parse_ty ctxt (pair_prim2 nat_prim_a nat_prim_b) pair_nat_a_nat_b_ty
@@ -277,13 +283,13 @@ let test_parse_comb_type () =
   (* pair (nat %a) (nat %b) (nat %c) *)
   pair_t
     (-1)
-    (nat_ty, Some (Field_annot "b"), None)
-    (nat_ty, Some (Field_annot "c"), None)
+    (nat_ty, Some (field_annot "b"), None)
+    (nat_ty, Some (field_annot "c"), None)
     ~annot:None
   >>??= fun pair_nat_b_nat_c_ty ->
   pair_t
     (-1)
-    (nat_ty, Some (Field_annot "a"), None)
+    (nat_ty, Some (field_annot "a"), None)
     (pair_nat_b_nat_c_ty, None, None)
     ~annot:None
   >>??= fun pair_nat_a_nat_b_nat_c_ty ->
@@ -297,8 +303,8 @@ let test_parse_comb_type () =
   >>??= fun pair_b_nat_nat_ty ->
   pair_t
     (-1)
-    (nat_ty, Some (Field_annot "a"), None)
-    (pair_b_nat_nat_ty, Some (Field_annot "b"), None)
+    (nat_ty, Some (field_annot "a"), None)
+    (pair_b_nat_nat_ty, Some (field_annot "b"), None)
     ~annot:None
   >>??= fun pair_nat_a_pair_b_nat_nat_ty ->
   test_parse_ty
@@ -351,7 +357,7 @@ let test_unparse_comb_type () =
   (* pair (nat %a) nat *)
   pair_t
     (-1)
-    (nat_ty, Some (Field_annot "a"), None)
+    (nat_ty, Some (field_annot "a"), None)
     (nat_ty, None, None)
     ~annot:None
   >>??= fun pair_nat_a_nat_ty ->
@@ -365,7 +371,7 @@ let test_unparse_comb_type () =
   pair_t
     (-1)
     (nat_ty, None, None)
-    (nat_ty, Some (Field_annot "b"), None)
+    (nat_ty, Some (field_annot "b"), None)
     ~annot:None
   >>??= fun pair_nat_nat_b_ty ->
   test_unparse_ty
@@ -377,8 +383,8 @@ let test_unparse_comb_type () =
   (* pair (nat %a) (nat %b) *)
   pair_t
     (-1)
-    (nat_ty, Some (Field_annot "a"), None)
-    (nat_ty, Some (Field_annot "b"), None)
+    (nat_ty, Some (field_annot "a"), None)
+    (nat_ty, Some (field_annot "b"), None)
     ~annot:None
   >>??= fun pair_nat_a_nat_b_ty ->
   test_unparse_ty
@@ -390,13 +396,13 @@ let test_unparse_comb_type () =
   (* pair (nat %a) (nat %b) (nat %c) *)
   pair_t
     (-1)
-    (nat_ty, Some (Field_annot "b"), None)
-    (nat_ty, Some (Field_annot "c"), None)
+    (nat_ty, Some (field_annot "b"), None)
+    (nat_ty, Some (field_annot "c"), None)
     ~annot:None
   >>??= fun pair_nat_b_nat_c_ty ->
   pair_t
     (-1)
-    (nat_ty, Some (Field_annot "a"), None)
+    (nat_ty, Some (field_annot "a"), None)
     (pair_nat_b_nat_c_ty, None, None)
     ~annot:None
   >>??= fun pair_nat_a_nat_b_nat_c_ty ->
@@ -411,8 +417,8 @@ let test_unparse_comb_type () =
   >>??= fun pair_nat_nat_ty ->
   pair_t
     (-1)
-    (nat_ty, Some (Field_annot "a"), None)
-    (pair_nat_nat_ty, Some (Field_annot "b"), None)
+    (nat_ty, Some (field_annot "a"), None)
+    (pair_nat_nat_ty, Some (field_annot "b"), None)
     ~annot:None
   >>??= fun pair_nat_a_pair_b_nat_nat_ty ->
   test_unparse_ty
@@ -425,7 +431,7 @@ let test_unparse_comb_type () =
   pair_t
     (-1)
     (nat_ty, None, None)
-    (pair_nat_nat_ty, None, Some (Var_annot "b"))
+    (pair_nat_nat_ty, None, Some (var_annot "b"))
     ~annot:None
   >>??= fun pair_nat_pair_b_nat_nat_ty ->
   test_unparse_ty
@@ -439,7 +445,7 @@ let test_unparse_comb_type () =
     (-1)
     (nat_ty, None, None)
     (nat_ty, None, None)
-    ~annot:(Some (Type_annot "b"))
+    ~annot:(Some (type_annot "b"))
   >>??= fun pair_b_nat_nat_ty ->
   pair_t (-1) (nat_ty, None, None) (pair_b_nat_nat_ty, None, None) ~annot:None
   >>??= fun pair_nat_pair_b_nat_nat_ty ->
@@ -495,7 +501,7 @@ let test_unparse_comb_comparable_type () =
     pair_nat_nat_nat_ty
   >>?= fun ctxt ->
   (* pair (nat %a) nat *)
-  pair_key (-1) (nat_ty, Some (Field_annot "a")) (nat_ty, None) ~annot:None
+  pair_key (-1) (nat_ty, Some (field_annot "a")) (nat_ty, None) ~annot:None
   >>??= fun pair_nat_a_nat_ty ->
   test_unparse_comparable_ty
     __LOC__
@@ -504,7 +510,7 @@ let test_unparse_comb_comparable_type () =
     pair_nat_a_nat_ty
   >>?= fun ctxt ->
   (* pair nat (nat %b) *)
-  pair_key (-1) (nat_ty, None) (nat_ty, Some (Field_annot "b")) ~annot:None
+  pair_key (-1) (nat_ty, None) (nat_ty, Some (field_annot "b")) ~annot:None
   >>??= fun pair_nat_nat_b_ty ->
   test_unparse_comparable_ty
     __LOC__
@@ -515,8 +521,8 @@ let test_unparse_comb_comparable_type () =
   (* pair (nat %a) (nat %b) *)
   pair_key
     (-1)
-    (nat_ty, Some (Field_annot "a"))
-    (nat_ty, Some (Field_annot "b"))
+    (nat_ty, Some (field_annot "a"))
+    (nat_ty, Some (field_annot "b"))
     ~annot:None
   >>??= fun pair_nat_a_nat_b_ty ->
   test_unparse_comparable_ty
@@ -528,13 +534,13 @@ let test_unparse_comb_comparable_type () =
   (* pair (nat %a) (nat %b) (nat %c) *)
   pair_key
     (-1)
-    (nat_ty, Some (Field_annot "b"))
-    (nat_ty, Some (Field_annot "c"))
+    (nat_ty, Some (field_annot "b"))
+    (nat_ty, Some (field_annot "c"))
     ~annot:None
   >>??= fun pair_nat_b_nat_c_ty ->
   pair_key
     (-1)
-    (nat_ty, Some (Field_annot "a"))
+    (nat_ty, Some (field_annot "a"))
     (pair_nat_b_nat_c_ty, None)
     ~annot:None
   >>??= fun pair_nat_a_nat_b_nat_c_ty ->
@@ -547,8 +553,8 @@ let test_unparse_comb_comparable_type () =
   (* pair (nat %a) (pair %b nat nat) *)
   pair_key
     (-1)
-    (nat_ty, Some (Field_annot "a"))
-    (pair_nat_nat_ty, Some (Field_annot "b"))
+    (nat_ty, Some (field_annot "a"))
+    (pair_nat_nat_ty, Some (field_annot "b"))
     ~annot:None
   >>??= fun pair_nat_a_pair_b_nat_nat_ty ->
   test_unparse_comparable_ty
@@ -558,7 +564,7 @@ let test_unparse_comb_comparable_type () =
     pair_nat_a_pair_b_nat_nat_ty
   >>?= fun ctxt ->
   (* pair nat (pair :b nat nat) *)
-  pair_key (-1) (nat_ty, None) (nat_ty, None) ~annot:(Some (Type_annot "b"))
+  pair_key (-1) (nat_ty, None) (nat_ty, None) ~annot:(Some (type_annot "b"))
   >>??= fun pair_b_nat_nat_ty ->
   pair_key (-1) (nat_ty, None) (pair_b_nat_nat_ty, None) ~annot:None
   >>??= fun pair_nat_pair_b_nat_nat_ty ->