diff --git a/src/proto_alpha/lib_protocol/sc_rollup_origination_machine.ml b/src/proto_alpha/lib_protocol/sc_rollup_origination_machine.ml
index da5b328b9aa2e693c459eec4025b458593d039be..baaf738154cc47c69557ab97d7f8579f7e813eda 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_origination_machine.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_origination_machine.ml
@@ -33,10 +33,6 @@ let void =
       (fun _ -> Error "void has no inhabitant")
       unit)
 
-type t = Context_binary.t
-
-type tree = Context_binary.tree
-
 let empty_tree () = Context_binary.(make_empty_context () |> Tree.empty)
 
 module Context_no_proofs = struct
@@ -57,22 +53,26 @@ module Context_no_proofs = struct
   let proof_encoding = void
 end
 
-module type S = Sc_rollup_PVM_sig.PROTO_ORIGINATION with type state = tree
+module type S = sig
+  include Sc_rollup_PVM_sig.PROTO_ORIGINATION
 
-module Arith : S = Sc_rollup_arith.Make (Context_no_proofs)
+  val empty_state : unit -> state
+end
 
-module Wasm : S =
-  Sc_rollup_wasm.V2_0_0.Make (Wasm_2_0_0.Make) (Context_no_proofs)
+module Arith : S = struct
+  include Sc_rollup_arith.Make (Context_no_proofs)
 
-module Riscv : S = struct
-  type state = tree
+  let empty_state = empty_tree
+end
 
-  type hash = Smart_rollup.State_hash.t
+module Wasm : S = struct
+  include Sc_rollup_wasm.V2_0_0.Make (Wasm_2_0_0.Make) (Context_no_proofs)
 
-  let state_hash _state =
-    Sc_rollup_riscv.(Protocol_implementation.state_hash (make_empty_state ()))
+  let empty_state = empty_tree
+end
 
-  let initial_state ~empty = Lwt.return empty
+module Riscv : S = struct
+  include Sc_rollup_riscv.Protocol_implementation
 
-  let install_boot_sector state _bs = Lwt.return state
+  let empty_state = Sc_rollup_riscv.make_empty_state
 end
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_origination_machine.mli b/src/proto_alpha/lib_protocol/sc_rollup_origination_machine.mli
index 0e3b7add1fe8816b7700d6069818e8da3c8ecb44..85f4aa7f53486212f4c5f6a2a0a9956fbc18d348 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_origination_machine.mli
+++ b/src/proto_alpha/lib_protocol/sc_rollup_origination_machine.mli
@@ -28,15 +28,11 @@
     be used to perform rollup origination, {b but} cannot be used to compute
     proofs or run computations. *)
 
-type void = |
+module type S = sig
+  include Sc_rollup_PVM_sig.PROTO_ORIGINATION
 
-type t = Context_binary.t
-
-type tree = Context_binary.tree
-
-val empty_tree : unit -> tree
-
-module type S = Sc_rollup_PVM_sig.PROTO_ORIGINATION with type state = tree
+  val empty_state : unit -> state
+end
 
 module Arith : S
 
diff --git a/src/proto_alpha/lib_protocol/sc_rollups.ml b/src/proto_alpha/lib_protocol/sc_rollups.ml
index 6058c4661aced88d02dc6332d48f72dcc953bce4..30ae99ccc450f140949bdec84f6fd2e221d97529 100644
--- a/src/proto_alpha/lib_protocol/sc_rollups.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollups.ml
@@ -107,7 +107,7 @@ end
 let genesis_state_hash_of ~boot_sector kind =
   let open Lwt_syntax in
   let (module Machine) = Kind.no_proof_machine_of kind in
-  let empty = Sc_rollup_origination_machine.empty_tree () in
+  let empty = Machine.empty_state () in
   let* tree = Machine.initial_state ~empty in
   let* tree = Machine.install_boot_sector tree boot_sector in
   Machine.state_hash tree