diff --git a/caisar.opam b/caisar.opam
index 81686d25b95a5b9b6a98f3f7f00647d6e5c58507..e3397717f6757d1b74cd46a4264e62c5762d3ca5 100644
--- a/caisar.opam
+++ b/caisar.opam
@@ -4,14 +4,13 @@ version: "0.1"
 synopsis: "Framework for neural network verification"
 depends: [
   "ocaml" {>= "4.10"}
-  "dune" {>= "2.9" & >= "2.9.0"}
+  "dune" {>= "2.9" & >= "2.9.1"}
   "dune-site" {>= "2.9.0"}
-  "why3"
   "piqi" {>= "0.7.6"}
   "piqilib" {>= "0.6.14"}
   "zarith" {>= "1.7"}
   "ocplib-endian" {>= "1.0"}
-  "dune" {>= "2.7" & >= "2.7.1"}
+  "dune" {>= "2.7.1"}
   "base" {>= "v0.14.0"}
   "stdio" {>= "v0.14.0"}
   "cmdliner" {>= "1.0.4"}
diff --git a/dune-project b/dune-project
index 21ab8e86ed506bfc685c1b6daf54d9f151462de9..6d2f7d9b515cb720b27b6cd863820f67e4996bf5 100644
--- a/dune-project
+++ b/dune-project
@@ -14,7 +14,7 @@
   (synopsis "Framework for neural network verification")
   (depends
    (ocaml (>= 4.10))
-   (dune (>= 2.9.0))
+   (dune (>= 2.9.1))
    (dune-site (>= 2.9.0))
    (piqi (>= 0.7.6))
    (piqilib (>= 0.6.14))
@@ -44,7 +44,17 @@
   (synopsis "NNet parser")
   (depends
    (ocaml (>= 4.10))
-   (dune (>= 2.7.1))
+   (dune (>= 2.9.1))
+   (base (>= v0.14.0))
+  )
+)
+
+(package
+  (name onnx)
+  (synopsis "ONNX parser")
+  (depends
+   (ocaml (>= 4.10))
+   (dune (>= 2.9.1))
    (base (>= v0.14.0))
   )
 )
diff --git a/lib/onnx/onnx.ml b/lib/onnx/onnx.ml
index e1ec0b4de7c851dd0962d7a2a0c0036129e6b105..5d6a9a8f7f73edcd52dde8dd34c137ad5b0e401f 100644
--- a/lib/onnx/onnx.ml
+++ b/lib/onnx/onnx.ml
@@ -16,9 +16,6 @@ type t = Opiqi.Model_proto.t
 
 (* ONNX format handling. *)
 
-let onnx_format_error s =
-  Error (Format.sprintf "ONNX format error: %s condition not satisfied." s)
-
 let parse_in_channel in_channel =
   let open Result in
   try
diff --git a/lib/onnx/onnx.mli b/lib/onnx/onnx.mli
index 437803c8e1bd9c10ace5b2157ef81048dc7005b1..3c70843567ff9bf1eaeb64b0f3b781c2f72e289a 100644
--- a/lib/onnx/onnx.mli
+++ b/lib/onnx/onnx.mli
@@ -4,21 +4,7 @@
 (*                                                                        *)
 (**************************************************************************)
 
-type t = private {
-  n_layers : int;  (** Number of layers. *)
-  n_inputs : int;  (** Number of inputs. *)
-  n_outputs : int;  (** Number of outputs. *)
-  max_layer_size : int;  (** Maximum layer size. *)
-  layer_sizes : int list;  (** Size of each layer. *)
-  min_input_values : float list;  (** Minimum values of inputs. *)
-  max_input_values : float list;  (** Maximum values of inputs. *)
-  mean_values : float list * float;
-    (** Mean values of inputs and one value for all outputs. *)
-  range_values : float list * float;
-    (** Range values of inputs and one value for all outputs. *)
-  weights_biases : float list list;  (** All weights and biases of NNet model. *)
-}
-(** NNet model metadata. *)
+type t = Onnx_piqi.Model_proto.t
 
 val parse : string -> (t, string) Result.t
-(** Parse an NNet file. *)
+(** Parse an ONNX file. *)
diff --git a/nnet.opam b/nnet.opam
index 4871796a4c568e4a3339f8a81b43c26d01c74ccd..dbc488d7ebd966482f56e88b31b7cb41a4d09c41 100644
--- a/nnet.opam
+++ b/nnet.opam
@@ -2,9 +2,17 @@
 opam-version: "2.0"
 version: "0.1"
 synopsis: "NNet parser"
+maintainer: ["Michele Alberti" "François Bobot" "Julien Girard-Satabin"]
+authors: [
+  "Michele Alberti"
+  "François Bobot"
+  "Julien Girard-Satabin"
+  "Zakaria Chihani"
+]
+bug-reports: "julien.girard2@cea.fr"
 depends: [
   "ocaml" {>= "4.10"}
-  "dune" {>= "2.9" & >= "2.7.1"}
+  "dune" {>= "2.9" & >= "2.9.1"}
   "base" {>= "v0.14.0"}
   "odoc" {with-doc}
 ]
diff --git a/onnx.opam b/onnx.opam
index a39060d3edf66c96a5d5f71319edae801221dc19..a37a869ed2dca7dcdc97c6707cfcf7e753c5b20b 100644
--- a/onnx.opam
+++ b/onnx.opam
@@ -2,14 +2,22 @@
 opam-version: "2.0"
 version: "0.1"
 synopsis: "ONNX parser"
+maintainer: ["Michele Alberti" "François Bobot" "Julien Girard-Satabin"]
+authors: [
+  "Michele Alberti"
+  "François Bobot"
+  "Julien Girard-Satabin"
+  "Zakaria Chihani"
+]
+bug-reports: "julien.girard2@cea.fr"
 depends: [
   "ocaml" {>= "4.10"}
-  "dune" {>= "2.9" & >= "2.7.1"}
+  "dune" {>= "2.9" & >= "2.9.1"}
   "base" {>= "v0.14.0"}
   "odoc" {with-doc}
 ]
 build: [
-  ["dune" "subst" "--root" "."] {dev}
+  ["dune" "subst"] {dev}
   [
     "dune"
     "build"
@@ -17,8 +25,7 @@ build: [
     name
     "-j"
     jobs
-    "--promote-install-files"
-    "false"
+    "--promote-install-files=false"
     "@install"
     "@runtest" {with-test}
     "@doc" {with-doc}
diff --git a/standalone/dune b/standalone/dune
index 60266cffc50bd0ab43de8b1a8a67a3af9733453e..7eea48208caf40bedaa33bff153a7a2118b9286f 100644
--- a/standalone/dune
+++ b/standalone/dune
@@ -12,10 +12,4 @@
   (libraries menhirLib yojson cmdliner logs logs.cli logs.fmt fmt.tty base unix str ppx_deriving_yojson.runtime)
   (preprocess (pps ppx_deriving_yojson ppx_deriving.show ppx_deriving.ord ppx_deriving.eq))
   (package caisar)
-  (libraries menhirLib yojson cmdliner logs logs.cli
-             ocplib-endian logs.fmt fmt.tty base unix str
-             ppx_deriving_yojson.runtime piqirun.pb zarith
-             stdio)
-  (preprocess (pps ppx_deriving_yojson ppx_deriving.show ppx_deriving.ord ppx_deriving.eq))
-  (package caisar)
 )