diff --git a/CHANGES.md b/CHANGES.md
index 8dc34def..cc554e18 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,5 @@
-Unreleased
------------
+0.9.0 2022-08-14
+---------------
 
 - h2: Fix tests on 32-bit platforms
   ([#152](https://github.com/anmonteiro/ocaml-h2/pull/152))
diff --git a/flake.nix b/flake.nix
index 233d3cf8..e0c9e486 100644
--- a/flake.nix
+++ b/flake.nix
@@ -11,11 +11,15 @@
       let
         pkgs = nixpkgs.legacyPackages."${system}".extend (self: super: {
           h2spec = super.callPackage ./nix/h2spec.nix { };
+          ocamlPackages = super.ocaml-ng.ocamlPackages_5_00;
         });
       in
       rec {
-        packages = (pkgs.callPackage ./nix { nix-filter = nix-filter.lib; });
+        packages = pkgs.callPackage ./nix { nix-filter = nix-filter.lib; };
         defaultPackage = packages.h2;
-        devShell = pkgs.callPackage ./shell.nix { };
+        devShells = rec {
+          default = pkgs.callPackage ./shell.nix { inherit packages; };
+          release = default.override { release-mode = true; };
+        };
       });
 }
diff --git a/shell.nix b/shell.nix
index 91fc844f..e8e51caf 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,12 +1,20 @@
-{ pkgs, stdenv, lib, release-mode ? false }:
+{ packages
+, mkShell
+, stdenv
+, lib
+, cacert
+, curl
+, ocamlPackages
+, git
+, h2spec
+, release-mode ? false
+}:
 
 let
-  h2Pkgs = pkgs.recurseIntoAttrs (import ./nix { inherit pkgs; doCheck = false; });
-  h2Drvs = lib.filterAttrs (_: value: lib.isDerivation value) h2Pkgs;
+  h2Drvs = lib.filterAttrs (_: value: lib.isDerivation value) packages;
 
 in
 
-with pkgs;
 
 (mkShell {
   inputsFrom = lib.attrValues h2Drvs;
@@ -16,7 +24,6 @@ with pkgs;
       curl
       ocamlPackages.dune-release
       git
-      opam
     ] else [ ])
     ++ (with ocamlPackages; [ merlin ocamlformat utop h2spec ]);
 }).overrideAttrs (o: {