diff --git a/pkgs/development/compilers/opa/default.nix b/pkgs/development/compilers/opa/default.nix
index e4cd191683c9..2843625daef2 100644
--- a/pkgs/development/compilers/opa/default.nix
+++ b/pkgs/development/compilers/opa/default.nix
@@ -73,6 +73,6 @@ stdenv.mkDerivation rec {
     homepage = "http://opalang.org/";
     license = lib.licenses.gpl3;
     maintainers = [ ];
-    platforms = with lib.platforms; unix;
+    platforms = [ "x86_64-linux" "x86_64-darwin" ];
   };
 }