From 2c9f03ff8188a418bb9329b5dbc4b75d168efd5a Mon Sep 17 00:00:00 2001
From: Vincent Laporte <Vincent.Laporte@gmail.com>
Date: Mon, 1 Jun 2015 22:36:00 +0200
Subject: [PATCH] ocaml-async: set attribute to null for unsupported OCaml
 versions

---
 pkgs/top-level/all-packages.nix | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 6c28a6c98c7..2a7c9a087c8 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -4104,7 +4104,10 @@ let
 
     async_unix = callPackage ../development/ocaml-modules/async_unix { };
 
-    async = callPackage ../development/ocaml-modules/async { };
+    async =
+      if lib.versionOlder "4.02" ocaml_version
+      then callPackage ../development/ocaml-modules/async { }
+      else null;
 
     atd = callPackage ../development/ocaml-modules/atd { };