diff --git a/src/util/Sidekick_util.ml b/src/util/Sidekick_util.ml
index a492a241..fda8f3a4 100644
--- a/src/util/Sidekick_util.ml
+++ b/src/util/Sidekick_util.ml
@@ -23,5 +23,6 @@ module Stat = Stat
 module Hash = Hash
 module Profile = Profile
 module Chunk_stack = Chunk_stack
+module Ser_value = Ser_value
 
 let[@inline] ( let@ ) f x = f x
diff --git a/src/util/ser_value.ml b/src/util/ser_value.ml
new file mode 100644
index 00000000..55eb7060
--- /dev/null
+++ b/src/util/ser_value.ml
@@ -0,0 +1,15 @@
+type t =
+  | Bool of bool
+  | Str of string
+  | Bytes of string
+  | Int of int
+  | List of t list
+  | Dict of t Util.Str_map.t
+
+let bool b : t = Bool b
+let int i : t = Int i
+let string x : t = Str x
+let bytes x : t = Bytes x
+let list x : t = List x
+let dict x : t = Dict x
+let dict_of_list l = dict (Util.Str_map.of_list l)
diff --git a/src/util/ser_value.mli b/src/util/ser_value.mli
new file mode 100644
index 00000000..da5a1aaf
--- /dev/null
+++ b/src/util/ser_value.mli
@@ -0,0 +1,23 @@
+(** Serialization representation.
+
+    A [Ser_value.t] describes how to serialized some structured
+    data into bytes.
+    It reflects the shape of the structured data but does not commit to a
+    particular serialization format.
+*)
+
+type t = private
+  | Bool of bool
+  | Str of string
+  | Bytes of string
+  | Int of int
+  | List of t list
+  | Dict of t Util.Str_map.t
+
+val bool : bool -> t
+val int : int -> t
+val string : string -> t
+val bytes : string -> t
+val list : t list -> t
+val dict : t Util.Str_map.t -> t
+val dict_of_list : (string * t) list -> t