diff --git a/src/proto_alpha/lib_protocol/alpha_context.mli b/src/proto_alpha/lib_protocol/alpha_context.mli
index 462b29885ef4c1580d13a3a298e73ce3f071e4af..e340830d818887a0a264618bcea2d8f072a835aa 100644
--- a/src/proto_alpha/lib_protocol/alpha_context.mli
+++ b/src/proto_alpha/lib_protocol/alpha_context.mli
@@ -2304,7 +2304,6 @@ module Tx_rollup_errors : sig
           [ `Valid_path of Tx_rollup_commitment.Merkle.h * int
           | `Hash of Tx_rollup_message_result_hash.t ];
       }
-    | Wrong_deposit_parameters
     | Proof_failed_to_reject
     | Proof_produced_rejected_state
     | Proof_invalid_before of {
diff --git a/src/proto_alpha/lib_protocol/apply.ml b/src/proto_alpha/lib_protocol/apply.ml
index 8b5bc41e532a05a251357a7eb1061cdd5e4687a2..23bdab2df0fc12f56357fbf4b9cce813fe5a7f4b 100644
--- a/src/proto_alpha/lib_protocol/apply.ml
+++ b/src/proto_alpha/lib_protocol/apply.ml
@@ -963,8 +963,9 @@ let apply_transaction_to_tx_rollup ~ctxt ~parameters_ty ~parameters ~payer
      returned using the L2 withdrawal mechanism: a failing
      deposit emits a withdrawal that can be executed by
      [payer]. *)
-  Tx_rollup_parameters.get_deposit_parameters parameters_ty parameters
-  >>?= fun {ex_ticket; l2_destination} ->
+  let Tx_rollup_parameters.{ex_ticket; l2_destination} =
+    Tx_rollup_parameters.get_deposit_parameters parameters_ty parameters
+  in
   ex_ticket_size ctxt ex_ticket >>=? fun (ctxt, ticket_size) ->
   let limit = Constants.tx_rollup_max_ticket_payload_size ctxt in
   fail_when
diff --git a/src/proto_alpha/lib_protocol/script_typed_ir.ml b/src/proto_alpha/lib_protocol/script_typed_ir.ml
index 9cc3a94ac81b429a89f943f2435f09e0242093df..e0371d154e5fe98d03cb033144792250d7e60f2a 100644
--- a/src/proto_alpha/lib_protocol/script_typed_ir.ml
+++ b/src/proto_alpha/lib_protocol/script_typed_ir.ml
@@ -1371,8 +1371,8 @@ and 'kind internal_operation_contents =
       -> Kind.transaction internal_operation_contents
   | Transaction_to_tx_rollup : {
       destination : Tx_rollup.t;
-      parameters_ty : ('a, _) ty;
-      parameters : 'a;
+      parameters_ty : (('a ticket, tx_rollup_l2_address) pair, _) ty;
+      parameters : ('a ticket, tx_rollup_l2_address) pair;
       unparsed_parameters : Script.expr;
     }
       -> Kind.transaction internal_operation_contents
diff --git a/src/proto_alpha/lib_protocol/script_typed_ir.mli b/src/proto_alpha/lib_protocol/script_typed_ir.mli
index da95bffff5f176f8a47c1d9cb0c2375874b116eb..2899f5ce523d0c331bcf0fac9b0dcbb4fa3a5921 100644
--- a/src/proto_alpha/lib_protocol/script_typed_ir.mli
+++ b/src/proto_alpha/lib_protocol/script_typed_ir.mli
@@ -1512,8 +1512,8 @@ and 'kind internal_operation_contents =
       -> Kind.transaction internal_operation_contents
   | Transaction_to_tx_rollup : {
       destination : Tx_rollup.t;
-      parameters_ty : ('a, _) ty;
-      parameters : 'a;
+      parameters_ty : (('a ticket, tx_rollup_l2_address) pair, _) ty;
+      parameters : ('a ticket, tx_rollup_l2_address) pair;
       unparsed_parameters : Script.expr;
     }
       -> Kind.transaction internal_operation_contents
diff --git a/src/proto_alpha/lib_protocol/ticket_operations_diff.ml b/src/proto_alpha/lib_protocol/ticket_operations_diff.ml
index 9bac8dc869f58efa792214fd72962ae47b22c1cd..c3db21d23593a404f1a8875569d2ef5e2977c1af 100644
--- a/src/proto_alpha/lib_protocol/ticket_operations_diff.ml
+++ b/src/proto_alpha/lib_protocol/ticket_operations_diff.ml
@@ -193,8 +193,9 @@ let tickets_of_operation ctxt ~allow_zero_amount_tickets
         ~parameters
   | Transaction_to_tx_rollup
       {destination; unparsed_parameters = _; parameters_ty; parameters} ->
-      Tx_rollup_parameters.get_deposit_parameters parameters_ty parameters
-      >>?= fun {ex_ticket; l2_destination = _} ->
+      let Tx_rollup_parameters.{ex_ticket; l2_destination = _} =
+        Tx_rollup_parameters.get_deposit_parameters parameters_ty parameters
+      in
       return
         ( Some
             {
diff --git a/src/proto_alpha/lib_protocol/tx_rollup_errors_repr.ml b/src/proto_alpha/lib_protocol/tx_rollup_errors_repr.ml
index a79f10792ef97a45a705b1e5eb6c7c17b9458dd7..6e14836718e8ed44c62a70b3d9512d0a992c662a 100644
--- a/src/proto_alpha/lib_protocol/tx_rollup_errors_repr.ml
+++ b/src/proto_alpha/lib_protocol/tx_rollup_errors_repr.ml
@@ -87,7 +87,6 @@ type error +=
         | `Hash of Tx_rollup_message_result_hash_repr.t ];
     }
   | Ticket_payload_size_limit_exceeded of {payload_size : int; limit : int}
-  | Wrong_deposit_parameters
   | Proof_failed_to_reject
   | Proof_produced_rejected_state
   | Proof_invalid_before of {agreed : Context_hash.t; provided : Context_hash.t}
diff --git a/src/proto_alpha/lib_protocol/tx_rollup_parameters.ml b/src/proto_alpha/lib_protocol/tx_rollup_parameters.ml
index 7c93e0a7f75e9ead3844e75f1ac63651e02b17ee..f79d341c7642621a0e12542bf0d6b4ab2b9bebf7 100644
--- a/src/proto_alpha/lib_protocol/tx_rollup_parameters.ml
+++ b/src/proto_alpha/lib_protocol/tx_rollup_parameters.ml
@@ -25,18 +25,18 @@
 (*                                                                           *)
 (*****************************************************************************)
 
+open Script_typed_ir
+
 type deposit_parameters = {
   ex_ticket : Ticket_scanner.ex_ticket;
-  l2_destination : Script_typed_ir.tx_rollup_l2_address;
+  l2_destination : tx_rollup_l2_address;
 }
 
 let get_deposit_parameters :
     type a comparable.
-    (a, comparable) Script_typed_ir.ty -> a -> deposit_parameters tzresult =
- fun ty contents ->
-  let open Script_typed_ir in
-  match (ty, contents) with
-  | ( Pair_t (Ticket_t (ty, _), Tx_rollup_l2_address_t, _, _),
-      (ticket, l2_destination) ) ->
-      ok {ex_ticket = Ticket_scanner.Ex_ticket (ty, ticket); l2_destination}
-  | _ -> error Alpha_context.Tx_rollup_errors.Wrong_deposit_parameters
+    ((a ticket, tx_rollup_l2_address) pair, comparable) ty ->
+    (a ticket, tx_rollup_l2_address) pair ->
+    deposit_parameters =
+ fun (Pair_t (Ticket_t (ty, _), Tx_rollup_l2_address_t, _, _))
+     (ticket, l2_destination) ->
+  {ex_ticket = Ticket_scanner.Ex_ticket (ty, ticket); l2_destination}
diff --git a/src/proto_alpha/lib_protocol/tx_rollup_parameters.mli b/src/proto_alpha/lib_protocol/tx_rollup_parameters.mli
index 8d240a428375885abe114567cd18bb693821da9f..76bd401277010e7d7f4313c2d0eb2a5d7731129f 100644
--- a/src/proto_alpha/lib_protocol/tx_rollup_parameters.mli
+++ b/src/proto_alpha/lib_protocol/tx_rollup_parameters.mli
@@ -28,22 +28,24 @@
 (** A module for representing and extracting typed transactional rollup
     parameters. *)
 
+open Script_typed_ir
+
 (** A type representing deposit parameters for transactional rollups. Deposit
     parameters consist of a ticket of arbitrary content along with a
     layer-2 destination address. *)
 type deposit_parameters = {
   ex_ticket : Ticket_scanner.ex_ticket;
-  l2_destination : Script_typed_ir.tx_rollup_l2_address;
+  l2_destination : tx_rollup_l2_address;
 }
 
 (** [get_deposit_parameters ty value] returns [ex_ticket] and a
-    [tx_rollup_l2_address] from a michelson typed value. if [ty] is not of a
-    pair of ticket and [tx_rollup_l2_address] then it fails with
-    [Tx_rollup_errors.Wrong_deposit_parameters].
+    [tx_rollup_l2_address] from a michelson typed value.
 
     This function is intended to be used to enforce the type of the transaction
     to a [tx_rollup%deposit]. It must be used both in [ticket_diffs_of_operations]
     to account for the ticket deposited and in [apply] to retrieve the ticket
     when applying the transaction to a tx_rollup. *)
 val get_deposit_parameters :
-  ('a, 'comparable) Script_typed_ir.ty -> 'a -> deposit_parameters tzresult
+  (('a ticket, tx_rollup_l2_address) pair, 'comparable) ty ->
+  ('a ticket, tx_rollup_l2_address) pair ->
+  deposit_parameters
diff --git a/src/proto_alpha/lib_tx_rollup/daemon.ml b/src/proto_alpha/lib_tx_rollup/daemon.ml
index 673e1dd72cd6caed6508568ba60b93c7d21b9484..2c8b32e864f057d733c1c1dcbee12fe0418c3047 100644
--- a/src/proto_alpha/lib_tx_rollup/daemon.ml
+++ b/src/proto_alpha/lib_tx_rollup/daemon.ml
@@ -53,14 +53,11 @@ let parse_ticketer : Script.node -> Contract.t tzresult =
   let open Micheline in
   function
   | Bytes (_loc, bytes) (* As unparsed with [Optimized]. *) ->
-      Result.of_option
-        ~error:
-          [Environment.wrap_tzerror Tx_rollup_errors.Wrong_deposit_parameters]
+      Result.of_option ~error:[Wrong_deposit_parameters]
       @@ Data_encoding.Binary.of_bytes_opt Contract.encoding bytes
   | String (_loc, str) (* As unparsed with [Readable]. *) ->
       Environment.wrap_tzresult @@ Contract.of_b58check str
-  | Int _ | Prim _ | Seq _ ->
-      error (Environment.wrap_tzerror Tx_rollup_errors.Wrong_deposit_parameters)
+  | Int _ | Prim _ | Seq _ -> error Wrong_deposit_parameters
 
 let parse_tx_rollup_deposit_parameters :
     Script.expr ->
diff --git a/src/proto_alpha/lib_tx_rollup/error.ml b/src/proto_alpha/lib_tx_rollup/error.ml
index fec8c73affbae21ae07d41bad1e27e195bd078ab..13277743addf7ee0a6ede59d810875e5dbf7d947 100644
--- a/src/proto_alpha/lib_tx_rollup/error.ml
+++ b/src/proto_alpha/lib_tx_rollup/error.ml
@@ -561,3 +561,5 @@ let () =
     Data_encoding.(obj1 (req "operation" Operation_hash.encoding))
     (function Tx_rollup_deposit_slashed o -> Some o | _ -> None)
     (fun o -> Tx_rollup_deposit_slashed o)
+
+type error += Wrong_deposit_parameters
diff --git a/src/proto_alpha/lib_tx_rollup/error.mli b/src/proto_alpha/lib_tx_rollup/error.mli
index 097c2a811136e81beb5b928b82259ce98ba69ce2..5c396b5a3671ec1510d545e304ad3eef74365ff6 100644
--- a/src/proto_alpha/lib_tx_rollup/error.mli
+++ b/src/proto_alpha/lib_tx_rollup/error.mli
@@ -132,3 +132,5 @@ type error += Tx_rollup_deposit_not_allowed
 
 (** Error (fatal) when we are slashed *)
 type error += Tx_rollup_deposit_slashed of Operation_hash.t
+
+type error += Wrong_deposit_parameters