diff --git a/pkgs/development/compilers/reason/tests/hello/default.nix b/pkgs/development/compilers/reason/tests/hello/default.nix
index 3def42ec08f7..831b528c6ba9 100644
--- a/pkgs/development/compilers/reason/tests/hello/default.nix
+++ b/pkgs/development/compilers/reason/tests/hello/default.nix
@@ -1,10 +1,18 @@
-{ buildDunePackage, ppxlib, reason }:
+{ lib, buildDunePackage, ppxlib, reason }:
 
 buildDunePackage rec {
   pname = "helloreason";
   version = "0.0.1";
 
-  src = ./.;
+  src = lib.fileset.toSource {
+    root = ./.;
+    fileset = lib.fileset.unions [
+      ./helloreason.opam
+      ./helloreason.re
+      ./dune-project
+      ./dune
+    ];
+  };
 
   nativeBuildInputs = [
     reason