diff --git a/src/aeso_ast_infer_types.erl b/src/aeso_ast_infer_types.erl
index f157eb7..a24aaea 100644
--- a/src/aeso_ast_infer_types.erl
+++ b/src/aeso_ast_infer_types.erl
@@ -359,7 +359,7 @@ global_env() ->
     Fun1    = fun(S, T) -> Fun([S], T) end,
     TVar    = fun(X) -> {tvar, Ann, "'" ++ X} end,
     SignId    = {id, Ann, "signature"},
-    SignDef   = {tuple, Ann, [{int, Ann, 0}, {int, Ann, 0}]},
+    SignDef   = {bytes, Ann, <<0:64/unit:8>>},
     Signature = {named_arg_t, Ann, SignId, SignId, {typed, Ann, SignDef, SignId}},
     SignFun   = fun(Ts, T) -> {type_sig, Ann, [Signature], Ts, T} end,
     TTL       = {qid, Ann, ["Chain", "ttl"]},
diff --git a/src/aeso_ast_to_fcode.erl b/src/aeso_ast_to_fcode.erl
index 1fac9ba..57ab3b3 100644
--- a/src/aeso_ast_to_fcode.erl
+++ b/src/aeso_ast_to_fcode.erl
@@ -294,6 +294,8 @@ type_to_fcode(Env, Sub, {tuple_t, _, Types}) ->
 type_to_fcode(Env, Sub, {record_t, Fields}) ->
     FieldType = fun({field_t, _, _, Ty}) -> Ty end,
     type_to_fcode(Env, Sub, {tuple_t, [], lists:map(FieldType, Fields)});
+type_to_fcode(_Env, _Sub, {bytes_t, _, _N}) ->
+    string; %% TODO: add bytes type to FATE?
 type_to_fcode(_Env, Sub, {tvar, _, X}) ->
     maps:get(X, Sub, any);
 type_to_fcode(_Env, _Sub, Type) ->
@@ -321,6 +323,8 @@ expr_to_fcode(_Env, _Type, {contract_pubkey, _, K}) -> {contract_pubkey, K};
 expr_to_fcode(_Env, _Type, {oracle_pubkey,   _, K}) -> {oracle_pubkey, K};
 expr_to_fcode(_Env, _Type, {oracle_query_id, _, K}) -> {oracle_query_id, K};
 
+expr_to_fcode(_Env, _Type, {bytes, _, Bin}) -> {string, Bin};
+
 %% Variables
 expr_to_fcode(Env, _Type, {id, _, X})  -> resolve_var(Env, [X]);
 expr_to_fcode(Env, _Type, {qid, _, X}) -> resolve_var(Env, X);