diff --git a/buildable.nix b/buildable.nix
index 35778c2..21af140 100644
--- a/buildable.nix
+++ b/buildable.nix
@@ -17,10 +17,12 @@ let
     );
   isReserved = n: builtins.elem n ["lib" "overlays" "modules"];
   isBroken = p: ({ meta.broken = false; } // p).meta.broken;
+  isFree = p: ({ meta.license.free = true; } // p).meta.license.free;
 in filterSet
      (n: !(isReserved n)) # filter out non-packages
      (p: (builtins.isAttrs p)
        && !(isBroken p)
+       && isFree p
      )
      (import ./default.nix { inherit pkgs; })