diff --git a/pkgs/development/ocaml-modules/dtoa/default.nix b/pkgs/development/ocaml-modules/dtoa/default.nix
index ffcfb38c6bf..866375cc5ba 100644
--- a/pkgs/development/ocaml-modules/dtoa/default.nix
+++ b/pkgs/development/ocaml-modules/dtoa/default.nix
@@ -1,21 +1,17 @@
-{ stdenv, lib, fetchurl, buildDunePackage, ounit }:
+{ stdenv, lib, fetchurl, buildDunePackage, ocaml, ounit2 }:
 
 buildDunePackage rec {
   pname = "dtoa";
-  version = "0.3.2";
-
-  useDune2 = true;
-
-  minimumOCamlVersion = "4.02";
+  version = "0.3.3";
 
   src = fetchurl {
-    url = "https://github.com/flowtype/ocaml-${pname}/releases/download/v${version}/${pname}-v${version}.tbz";
-    sha256 = "0zkhn0rdq82g6gamsv6nkx6i44s8104nh6jg5xydazl9jl1704xn";
+    url = "https://github.com/flowtype/ocaml-${pname}/releases/download/v${version}/${pname}-${version}.tbz";
+    hash = "sha256-2PRgjJ6Ssp4l6jHzv1/MqzlomQlJkKLVnRXG6KPJ7j4=";
   };
 
-  checkInputs = [ ounit ];
+  checkInputs = [ ounit2 ];
 
-  doCheck = true;
+  doCheck = lib.versionAtLeast ocaml.version "4.08";
 
   hardeningDisable = lib.optional stdenv.cc.isClang "strictoverflow";