diff --git a/git-kv.opam b/git-kv.opam
index 00f9963..eba381c 100644
--- a/git-kv.opam
+++ b/git-kv.opam
@@ -12,7 +12,8 @@ depends: [
   "dune"              {>= "2.9.0"}
   "git"               {>= "3.10.0"}
   "mirage-kv"         {>= "6.0.0"}
-  "carton"            {>= "0.6.0"}
+  "carton"            {>= "0.7.0"}
+  "carton-lwt"        {>= "0.7.0"}
   "fmt"               {>= "0.8.7"}
   "mirage-clock"      {>= "2.0.0"}
   "ptime"
diff --git a/src/git_kv.ml b/src/git_kv.ml
index d46fec2..15b9802 100644
--- a/src/git_kv.ml
+++ b/src/git_kv.ml
@@ -183,7 +183,7 @@ let ( >>? ) x f = let open Lwt.Infix in match x with
   | None -> Lwt.return_none
 let ( >>! ) x f = Lwt.Infix.(x >>= f)
 
-let pack t ~commit stream =
+let pack t ?(level= 4) ~commit stream =
   let open Lwt.Infix in
   let load t hash =
     Store.read_inflated t hash >|= function
@@ -227,7 +227,7 @@ let pack t ~commit stream =
     | Some None -> failwith "Try to encode an OBJ_REF object" (* XXX(dinosaure): should never occur! *)
     | Some (Some (_ (* offset *) : int)) | None ->
       Hashtbl.add offsets (Carton.Enc.target_uid targets.(idx)) !cursor ;
-      Carton_lwt.Enc.encode_target ~b ~find ~load:(load t) ~uid targets.(idx) ~cursor:(Int64.to_int !cursor)
+      Carton_lwt.Enc.encode_target ~level ~b ~find ~load:(load t) ~uid targets.(idx) ~cursor:(Int64.to_int !cursor)
       >>= fun (len, encoder) ->
       let payload = Bigstringaf.substring b.o ~off:0 ~len in
       stream (Some payload) ;
@@ -254,7 +254,7 @@ let pack t ~commit stream =
   stream None ;
   Lwt.return_unit
 
-let to_octets t = match t.head with
+let to_octets ?level t = match t.head with
   | None ->
     Lwt.return "PACK\000\000\000\002\000\000\000\000\
                 \x02\x9d\x08\x82\x3b\xd8\xa8\xea\xb5\x10\xad\x6a\xc7\x5c\x82\x3c\xfd\x3e\xd3\x1e"
@@ -262,7 +262,7 @@ let to_octets t = match t.head with
     let buf = Buffer.create 0x100 in
     let stream = Option.iter (Buffer.add_string buf) in
     let open Lwt.Infix in
-    pack t.store ~commit stream >|= fun () ->
+    pack ?level t.store ~commit stream >|= fun () ->
     Buffer.contents buf
 
 (* XXX(dinosaure): we have the full-control between [to_octets]/[of_octets]
diff --git a/src/git_kv.mli b/src/git_kv.mli
index bfc0020..2a72f53 100644
--- a/src/git_kv.mli
+++ b/src/git_kv.mli
@@ -43,8 +43,10 @@ val connect : Mimic.ctx -> string -> t Lwt.t
 val branch : t -> Git.Reference.t
 (** [branch t] returns the branch used by the given [t]. *)
 
-val to_octets : t -> string Lwt.t
-(** [to_octets store] returns a serialized version of the given [store]. *)
+val to_octets : ?level:int -> t -> string Lwt.t
+(** [to_octets ?level store] returns a serialized version of the given [store].
+    [level] is the {i zlib} level compression used for Git object (between [0]
+    and [9] including), defaults to [4]. *)
 
 val of_octets : Mimic.ctx -> remote:string -> string ->
   (t, [> `Msg of string]) result Lwt.t