diff --git a/pkgs/tools/package-management/smlpkg/default.nix b/pkgs/tools/package-management/smlpkg/default.nix
index f3f7750f1bdd..b92ced4842a0 100644
--- a/pkgs/tools/package-management/smlpkg/default.nix
+++ b/pkgs/tools/package-management/smlpkg/default.nix
@@ -37,6 +37,7 @@ stdenv.mkDerivation rec {
     description = "Generic package manager for Standard ML libraries and programs";
     homepage = "https://github.com/diku-dk/smlpkg";
     license = licenses.mit;
+    platforms = mlton.meta.platforms;
     maintainers = with maintainers; [ athas ];
   };
 }