diff --git a/pkgs/development/ocaml-modules/mirage-bootvar-unix/default.nix b/pkgs/development/ocaml-modules/mirage-bootvar-unix/default.nix
index 3adb2349092e..5c6f364d1343 100644
--- a/pkgs/development/ocaml-modules/mirage-bootvar-unix/default.nix
+++ b/pkgs/development/ocaml-modules/mirage-bootvar-unix/default.nix
@@ -6,15 +6,13 @@
   parse-argv,
 }:
 
-buildDunePackage rec {
+buildDunePackage (finalAttrs: {
   pname = "mirage-bootvar-unix";
   version = "0.1.0";
 
-  useDune2 = true;
-
   src = fetchurl {
-    url = "https://github.com/mirage/mirage-bootvar-unix/releases/download/${version}/mirage-bootvar-unix-${version}.tbz";
-    sha256 = "0r92s6y7nxg0ci330a7p0hii4if51iq0sixn20cnm5j4a2clprbf";
+    url = "https://github.com/mirage/mirage-bootvar-unix/releases/download/${finalAttrs.version}/mirage-bootvar-unix-${finalAttrs.version}.tbz";
+    hash = "sha256-buVLmVBElmoZELZHDXAMxUUSIwT3KDBGZOB1e7zRImU=";
   };
 
   propagatedBuildInputs = [
@@ -28,4 +26,4 @@ buildDunePackage rec {
     license = lib.licenses.isc;
     maintainers = [ lib.maintainers.vbgl ];
   };
-}
+})