diff --git a/.travis.yml b/.travis.yml
index 66ece26..e1d6117 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -22,7 +22,7 @@ install:
  - travis_retry nix-channel --update
 
 script:
- - outs=$(nix-build non-broken.nix) && echo Produced $outs
+ - outs=$(nix-build buildable.nix) && echo Produced $outs
  - nix eval -f default.nix 'lib'
  - nix eval -f default.nix 'modules'
  - nix eval -f default.nix 'overlays'
diff --git a/buildable.nix b/buildable.nix
new file mode 100644
index 0000000..2b61b1f
--- /dev/null
+++ b/buildable.nix
@@ -0,0 +1,28 @@
+# This file filters out all the unbuildable packages from your package set.
+# It's what gets built by CI, so if you correctly mark broken/unfree packages
+# as such your CI will not try to build them and the buildable packages will
+# be added to the cache.
+{ pkgs ? import <nixpkgs> {} }:
+
+let
+  filterSet =
+    (f: g: s: builtins.listToAttrs
+      (map
+        (n: { name = n; value = builtins.getAttr n s; })
+        (builtins.filter
+          (n: f n && g (builtins.getAttr n s))
+          (builtins.attrNames s)
+        )
+      )
+    );
+  isReserved = n: builtins.elem n ["lib" "overlays" "modules"];
+  isBroken = p: p.meta.broken or false;
+  isFree = p: p.meta.license.free or true;
+in filterSet
+     (n: !(isReserved n)) # filter out non-packages
+     (p: (builtins.isAttrs p)
+       && !(isBroken p)
+       && isFree p
+     )
+     (import ./default.nix { inherit pkgs; })
+
diff --git a/non-broken.nix b/non-broken.nix
deleted file mode 100644
index b9a2cf9..0000000
--- a/non-broken.nix
+++ /dev/null
@@ -1,27 +0,0 @@
-# This file filters out all the broken packages from your package set.
-# It's what gets built by CI, so if you correctly mark broken packages as
-# broken your CI will not try to build them and the non-broken packages will
-# be added to the cache.
-{ pkgs ? import <nixpkgs> {} }:
-
-let filterSet =
-      (f: g: s: builtins.listToAttrs
-        (map
-          (n: { name = n; value = builtins.getAttr n s; })
-          (builtins.filter
-            (n: f n && g (builtins.getAttr n s))
-            (builtins.attrNames s)
-          )
-        )
-      );
-in filterSet
-     (n: !(n=="lib"||n=="overlays"||n=="modules")) # filter out non-packages
-     (p: (builtins.isAttrs p)
-       && !(
-             (builtins.hasAttr "meta" p)
-             && (builtins.hasAttr "broken" p.meta)
-             && (p.meta.broken)
-           )
-     )
-     (import ./default.nix { inherit pkgs; })
-
diff --git a/overlay.nix b/overlay.nix
index 082b038..bda4332 100644
--- a/overlay.nix
+++ b/overlay.nix
@@ -4,18 +4,20 @@
 
 self: super:
 
-let filterSet =
-      (f: g: s: builtins.listToAttrs
-        (map
-          (n: { name = n; value = builtins.getAttr n s; })
-          (builtins.filter
-            (n: f n && g (builtins.getAttr n s))
-            (builtins.attrNames s)
-          )
+let
+  filterSet =
+    (f: g: s: builtins.listToAttrs
+      (map
+        (n: { name = n; value = builtins.getAttr n s; })
+        (builtins.filter
+          (n: f n && g (builtins.getAttr n s))
+          (builtins.attrNames s)
         )
-      );
+      )
+    );
+  isReserved = n: builtins.elem n ["lib" "overlays" "modules"];
 in filterSet
-     (n: !(n=="lib"||n=="overlays"||n=="modules")) # filter out non-packages
+     (n: !(isReserved n)) # filter out non-packages
      (p: true) # all packages are ok
      (import ./default.nix { pkgs = super; })