diff --git a/src/lib_scoru_wasm/durable.ml b/src/lib_scoru_wasm/durable.ml
index b79d83b40540f7a7d9dc9a12f908392227501046..bfce97b469d1025794c18ef6761f9fdce9fd6ffb 100644
--- a/src/lib_scoru_wasm/durable.ml
+++ b/src/lib_scoru_wasm/durable.ml
@@ -169,15 +169,26 @@ let move_tree_exn tree from_key to_key =
   let* tree = delete tree from_key in
   T.add_tree tree (key_contents to_key) move_tree
 
-let hash tree key =
+let hash ~kind tree key =
   let open Lwt.Syntax in
-  let+ opt = T.find_tree tree @@ to_value_key @@ key_contents key in
+  let key =
+    match kind with
+    | `Value -> to_value_key (key_contents key)
+    | `Subtree -> key_contents key
+  in
+  let+ opt = T.find_tree tree key in
   Option.map (fun subtree -> T.hash subtree) opt
 
-let hash_exn tree key =
+let hash_exn ~kind tree key =
   let open Lwt.Syntax in
-  let+ opt = hash tree key in
-  match opt with None -> raise Value_not_found | Some hash -> hash
+  let+ opt = hash ~kind tree key in
+  match opt with
+  | None ->
+      let exn =
+        match kind with `Value -> Value_not_found | `Subtree -> Tree_not_found
+      in
+      raise exn
+  | Some hash -> hash
 
 let set_value_exn tree ?(edit_readonly = false) key str =
   if not edit_readonly then assert_key_writeable key ;
diff --git a/src/lib_scoru_wasm/durable.mli b/src/lib_scoru_wasm/durable.mli
index 9b252beb4e95c20bf9963a99c9697b2457a9a958..0e741208b6a9a2865198cdc03bfebd771fc27989 100644
--- a/src/lib_scoru_wasm/durable.mli
+++ b/src/lib_scoru_wasm/durable.mli
@@ -121,17 +121,18 @@ val subtree_name_at : t -> key -> int -> string Lwt.t
 *)
 val delete : ?edit_readonly:bool -> t -> key -> t Lwt.t
 
-(** [hash durable key] retrieves the tree hash of the value at the given [key].
-    This is not the same as the hash of the value.
-*)
-val hash : t -> key -> Context_hash.t option Lwt.t
-
-(** [hash_exn durable key] retrieves the tree hash of the value at the given [key].
-    This is not the same as the hash of the value.
-
-    @raise Value_not_found when [key] is not found
-*)
-val hash_exn : t -> key -> Context_hash.t Lwt.t
+(** [hash ~kind durable key] retrieves the tree hash of the value (if
+    [kind = `Value]) or the subtree ([kind = `Subtree]) at the given
+    [key].  This is not the same as the hash of the value. *)
+val hash : kind:[`Value | `Subtree] -> t -> key -> Context_hash.t option Lwt.t
+
+(** [hash_exn ~kind durable key] retrieves the tree hash of the value
+    (if [kind = `Value]) or the subtree ([kind = `Subtree]) at the
+    given [key]. This is not the same as the hash of the value.
+
+    @raise Value_not_found when [key] is not found and [kind = `Subtree]
+    @raise Tree_not_found when [key] is not found and [kind = `Value]. *)
+val hash_exn : kind:[`Value | `Subtree] -> t -> key -> Context_hash.t Lwt.t
 
 (** [set_value_exn durable key str] installs the value [str] in
     [durable] under [key], replacing any previous contents under this
diff --git a/src/lib_scoru_wasm/fast/module_cache.ml b/src/lib_scoru_wasm/fast/module_cache.ml
index 77d5a705984cbf3de595ccd17848d759713788d0..411ce80eaad3091baaedde68d9a4d3fa2b63b970 100644
--- a/src/lib_scoru_wasm/fast/module_cache.ml
+++ b/src/lib_scoru_wasm/fast/module_cache.ml
@@ -44,7 +44,7 @@ let load_parse_module store key durable =
 
 let load_module store key durable =
   let open Lwt.Syntax in
-  let* kernel_hash = Durable.hash_exn durable key in
+  let* kernel_hash = Durable.hash_exn ~kind:`Value durable key in
   let md = Kernel_cache.find_opt kernel_cache kernel_hash in
   match md with
   | None ->
diff --git a/src/lib_scoru_wasm/test/durable_snapshot/durable.ml b/src/lib_scoru_wasm/test/durable_snapshot/durable.ml
index 6142addc884aede05c9eead706f9aa442b8c2de7..f7a790f5b426fc9d9454096cf60efef67d5a5050 100644
--- a/src/lib_scoru_wasm/test/durable_snapshot/durable.ml
+++ b/src/lib_scoru_wasm/test/durable_snapshot/durable.ml
@@ -173,15 +173,26 @@ let move_tree_exn tree from_key to_key =
   let* tree = delete tree from_key in
   T.add_tree tree (key_contents to_key) move_tree
 
-let hash tree key =
+let hash ~kind tree key =
   let open Lwt.Syntax in
-  let+ opt = T.find_tree tree @@ to_value_key @@ key_contents key in
+  let key =
+    match kind with
+    | `Value -> to_value_key (key_contents key)
+    | `Subtree -> key_contents key
+  in
+  let+ opt = T.find_tree tree key in
   Option.map (fun subtree -> T.hash subtree) opt
 
-let hash_exn tree key =
+let hash_exn ~kind tree key =
   let open Lwt.Syntax in
-  let+ opt = hash tree key in
-  match opt with None -> raise Value_not_found | Some hash -> hash
+  let+ opt = hash ~kind tree key in
+  match opt with
+  | None ->
+      let exn =
+        match kind with `Value -> Value_not_found | `Subtree -> Tree_not_found
+      in
+      raise exn
+  | Some hash -> hash
 
 let set_value_exn tree ?(edit_readonly = false) key str =
   if not edit_readonly then assert_key_writeable key ;
diff --git a/src/lib_scoru_wasm/test/durable_snapshot/durable.mli b/src/lib_scoru_wasm/test/durable_snapshot/durable.mli
index 99d6e1e04ae14dad56fe49621a57c7b0112c1d5f..f1388be09e9a3ebff84d11c951c7a4891423ef94 100644
--- a/src/lib_scoru_wasm/test/durable_snapshot/durable.mli
+++ b/src/lib_scoru_wasm/test/durable_snapshot/durable.mli
@@ -23,7 +23,7 @@
 (*                                                                           *)
 (*****************************************************************************)
 
-(* Version of durable storage corresponding to
+(* Version of durable storage initially corresponding to
    https://gitlab.com/tezos/tezos/-/blob/668fe735aa20ce0c68b9f836208e57fa15d389c1/src/lib_scoru_wasm/durable.mli
 *)
 
@@ -125,17 +125,17 @@ val subtree_name_at : t -> key -> int -> string Lwt.t
 *)
 val delete : ?edit_readonly:bool -> t -> key -> t Lwt.t
 
-(** [hash durable key] retrieves the tree hash of the value at the given [key].
-    This is not the same as the hash of the value.
-*)
-val hash : t -> key -> Context_hash.t option Lwt.t
+(** [hash ~kind durable key] retrieves the tree hash of the value (if
+    [kind = `Value]) or the subtree ([kind = `Subtree]) at the given
+    [key].  This is not the same as the hash of the value. *)
+val hash : kind:[`Value | `Subtree] -> t -> key -> Context_hash.t option Lwt.t
 
-(** [hash_exn durable key] retrieves the tree hash of the value at the given [key].
-    This is not the same as the hash of the value.
+(** [hash_exn ~kind durable key] retrieves the tree hash of the value
+    (if [kind = `Value]) or the subtree ([kind = `Subtree]) at the
+    given [key]. This is not the same as the hash of the value.
 
-    @raise Value_not_found when [key] is not found
-*)
-val hash_exn : t -> key -> Context_hash.t Lwt.t
+    @raise Value_not_found when [key] is not found *)
+val hash_exn : kind:[`Value | `Subtree] -> t -> key -> Context_hash.t Lwt.t
 
 (** [set_value_exn durable key str] installs the value [str] in
     [durable] under [key], replacing any previous contents under this
diff --git a/src/lib_scoru_wasm/test/helpers/durable_operation.ml b/src/lib_scoru_wasm/test/helpers/durable_operation.ml
index 43754ba661e3d3e6743659865713b53638d7f826..3aff540e798c544a2f89b83aec81d62b77734232 100644
--- a/src/lib_scoru_wasm/test/helpers/durable_operation.ml
+++ b/src/lib_scoru_wasm/test/helpers/durable_operation.ml
@@ -32,6 +32,8 @@ let key_to_str key_list = String.concat "/" ("" :: key_list)
 let key_len key_list =
   List.fold_left (fun acc seg -> String.length seg + acc + 1) 0 ("" :: key_list)
 
+let kind_to_str = function `Value -> "Value" | `Subtree -> "Subtree"
+
 (* GADT type, each constructor's type represents a type parameters
    which are taken as input of corresponding operation *)
 type _ operation_kind =
@@ -54,9 +56,9 @@ type _ operation_kind =
   (* key, idx*)
   | Substree_name_at : (key * int) operation_kind
   (* key *)
-  | Hash : key operation_kind
+  | Hash : (key * [`Value | `Subtree]) operation_kind
   (* key *)
-  | Hash_exn : key operation_kind
+  | Hash_exn : (key * [`Value | `Subtree]) operation_kind
   (* edit_readonly, key, offset, value *)
   | Write_value_exn : (bool * key * int64 * string) operation_kind
   (* key, offset, len *)
@@ -144,10 +146,22 @@ let pp fmt (x : t) =
         Substree_name_at
         (key_to_str key)
         idx
-  | Operation (Hash, key) ->
-      Format.fprintf fmt "%a(%s)" pp_operation_kind Hash (key_to_str key)
-  | Operation (Hash_exn, key) ->
-      Format.fprintf fmt "%a(%s)" pp_operation_kind Hash_exn (key_to_str key)
+  | Operation (Hash, (key, kind)) ->
+      Format.fprintf
+        fmt
+        "%a(key: %s, kind: %s)"
+        pp_operation_kind
+        Hash
+        (key_to_str key)
+        (kind_to_str kind)
+  | Operation (Hash_exn, (key, kind)) ->
+      Format.fprintf
+        fmt
+        "%a(key: %s, kind: %s)"
+        pp_operation_kind
+        Hash_exn
+        (key_to_str key)
+        (kind_to_str kind)
   | Operation (Write_value_exn, (edit_readonly, key, offset, _value)) ->
       Format.fprintf
         fmt
diff --git a/src/lib_scoru_wasm/test/helpers/durable_operation_generator.ml b/src/lib_scoru_wasm/test/helpers/durable_operation_generator.ml
index b1274cbc81e7ac8df43d762a5591e2051794652a..8a1e914d3cac7553297ffe6fa5c7676960ad3923 100644
--- a/src/lib_scoru_wasm/test/helpers/durable_operation_generator.ml
+++ b/src/lib_scoru_wasm/test/helpers/durable_operation_generator.ml
@@ -386,23 +386,25 @@ let gen_subtree_name_at trie =
 
 let gen_hash trie =
   let open Gen in
-  let+ key =
+  let* key =
     gen_key
       ~key_exists:Operation_probabilities.key_exists_in_read_operation
       ~prefix_exists:Operation_probabilities.prefix_exists_in_operation
       trie
   in
-  Operation (Hash, key)
+  let+ kind = oneofl [`Value; `Subtree] in
+  Operation (Hash, (key, kind))
 
 let gen_hash_exn trie =
   let open Gen in
-  let+ key =
+  let* key =
     gen_key
       ~key_exists:Operation_probabilities.key_exists_in_read_operation
       ~prefix_exists:Operation_probabilities.prefix_exists_in_operation
       trie
   in
-  Operation (Hash_exn, key)
+  let+ kind = oneofl [`Value; `Subtree] in
+  Operation (Hash_exn, (key, kind))
 
 let gen_write_value_exn trie =
   let open Gen in
diff --git a/src/lib_scoru_wasm/test/helpers/durable_program_runner.ml b/src/lib_scoru_wasm/test/helpers/durable_program_runner.ml
index ec0f8239eea85e0db3ff4145205cfc8b6feebb3e..6e79453ac42eb5d2145048aa9e0e11a2426597be 100644
--- a/src/lib_scoru_wasm/test/helpers/durable_program_runner.ml
+++ b/src/lib_scoru_wasm/test/helpers/durable_program_runner.ml
@@ -165,14 +165,16 @@ struct
                  dur
                  (Durable.key_of_string_exn @@ Durable_operation.key_to_str key)
                  idx
-        | Operation (Hash, key) ->
+        | Operation (Hash, (key, kind)) ->
             value_res
             @@ Durable.hash
+                 ~kind
                  dur
                  (Durable.key_of_string_exn @@ Durable_operation.key_to_str key)
-        | Operation (Hash_exn, key) ->
+        | Operation (Hash_exn, (key, kind)) ->
             value_res
             @@ Durable.hash_exn
+                 ~kind
                  dur
                  (Durable.key_of_string_exn @@ Durable_operation.key_to_str key)
         | Operation (Write_value_exn, (edit_readonly, key, offset, value)) ->
diff --git a/src/lib_scoru_wasm/test/helpers/durable_snapshot_util.ml b/src/lib_scoru_wasm/test/helpers/durable_snapshot_util.ml
index d6ac91ad88fdf3f1bdf58ca04e45a1e2799bc242..41b6aa7f80828578e0d6695071b5dd883eded28f 100644
--- a/src/lib_scoru_wasm/test/helpers/durable_snapshot_util.ml
+++ b/src/lib_scoru_wasm/test/helpers/durable_snapshot_util.ml
@@ -60,9 +60,9 @@ module type Testable_durable_sig = sig
 
   val delete : ?edit_readonly:bool -> t -> key -> t Lwt.t
 
-  val hash : t -> key -> Context_hash.t option Lwt.t
+  val hash : kind:[`Subtree | `Value] -> t -> key -> Context_hash.t option Lwt.t
 
-  val hash_exn : t -> key -> Context_hash.t Lwt.t
+  val hash_exn : kind:[`Subtree | `Value] -> t -> key -> Context_hash.t Lwt.t
 
   val set_value_exn : t -> ?edit_readonly:bool -> key -> string -> t Lwt.t
 
@@ -369,19 +369,19 @@ end) : Testable_durable_sig with type t = Snapshot.t * Current.t = struct
       (fun () -> Snapshot.delete ?edit_readonly tree_s key_s)
       (fun () -> Current.delete ?edit_readonly tree_c key_c)
 
-  let hash (tree_s, tree_c) (key_s, key_c) =
+  let hash ~kind (tree_s, tree_c) (key_s, key_c) =
     same_values
       ~pp:(Fmt.option Context_hash.pp)
       ~eq:(Option.equal Context_hash.equal)
-      (fun () -> add_tree tree_s @@ Snapshot.hash tree_s key_s)
-      (fun () -> add_tree tree_c @@ Current.hash tree_c key_c)
+      (fun () -> add_tree tree_s @@ Snapshot.hash ~kind tree_s key_s)
+      (fun () -> add_tree tree_c @@ Current.hash ~kind tree_c key_c)
 
-  let hash_exn (tree_s, tree_c) (key_s, key_c) =
+  let hash_exn ~kind (tree_s, tree_c) (key_s, key_c) =
     same_values
       ~pp:Context_hash.pp
       ~eq:Context_hash.equal
-      (fun () -> add_tree tree_s @@ Snapshot.hash_exn tree_s key_s)
-      (fun () -> add_tree tree_c @@ Current.hash_exn tree_c key_c)
+      (fun () -> add_tree tree_s @@ Snapshot.hash_exn ~kind tree_s key_s)
+      (fun () -> add_tree tree_c @@ Current.hash_exn ~kind tree_c key_c)
 
   let set_value_exn (tree_s, tree_c) ?edit_readonly (key_s, key_c) bytes =
     same_trees
@@ -557,16 +557,19 @@ module Traceable_durable = struct
         (Fun.const true)
       @@ fun () -> D.delete ~edit_readonly dur key
 
-    let hash dur key =
-      inspect_op Hash (D.Internal_for_tests.key_to_list key) Option.is_some
-      @@ fun () -> D.hash dur key
+    let hash ~kind dur key =
+      inspect_op
+        Hash
+        (D.Internal_for_tests.key_to_list key, kind)
+        Option.is_some
+      @@ fun () -> D.hash ~kind dur key
 
-    let hash_exn dur key =
+    let hash_exn ~kind dur key =
       inspect_op
         Hash_exn
-        (D.Internal_for_tests.key_to_list key)
+        (D.Internal_for_tests.key_to_list key, kind)
         (Fun.const true)
-      @@ fun () -> D.hash_exn dur key
+      @@ fun () -> D.hash_exn ~kind dur key
 
     let set_value_exn dur ?(edit_readonly = false) key value =
       inspect_op
diff --git a/src/lib_scoru_wasm/wasm_vm.ml b/src/lib_scoru_wasm/wasm_vm.ml
index 0df600753f17eff808ce8d6982598b1d764eaff6..4181fd8f701bf8111d6e6614faa5935dc854b1bb 100644
--- a/src/lib_scoru_wasm/wasm_vm.ml
+++ b/src/lib_scoru_wasm/wasm_vm.ml
@@ -104,8 +104,10 @@ let mark_for_reboot {reboot_counter; durable; _} =
    the currently running kernel. *)
 let has_fallback_kernel durable =
   let open Lwt_syntax in
-  let* kernel_hash = Durable.hash durable Constants.kernel_key in
-  let+ fallback_hash = Durable.hash durable Constants.kernel_fallback_key in
+  let* kernel_hash = Durable.hash ~kind:`Value durable Constants.kernel_key in
+  let+ fallback_hash =
+    Durable.hash ~kind:`Value durable Constants.kernel_fallback_key
+  in
   Option.is_some fallback_hash && kernel_hash <> fallback_hash
 
 let initial_boot_state () =
@@ -115,9 +117,9 @@ let initial_boot_state () =
 
 let save_fallback_kernel durable =
   let open Lwt.Syntax in
-  let* kernel_hash = Durable.hash durable Constants.kernel_key in
+  let* kernel_hash = Durable.hash ~kind:`Value durable Constants.kernel_key in
   let* kernel_fallback_hash =
-    Durable.hash durable Constants.kernel_fallback_key
+    Durable.hash ~kind:`Value durable Constants.kernel_fallback_key
   in
   if kernel_hash <> kernel_fallback_hash then
     Durable.copy_tree_exn