diff --git a/nix/default.nix b/nix/default.nix
new file mode 100644
index 0000000..c2e96f9
--- /dev/null
+++ b/nix/default.nix
@@ -0,0 +1,31 @@
+{ sourcePaths ? import ./sources.nix
+, system ? builtins.currentSystem
+, crossSystem ? null
+, config ? {} }:
+
+let
+  # our own overlays:
+  local-overlays = [
+  ];
+
+  globals =
+    if builtins.pathExists ../globals.nix
+    then [(import ../globals.nix)]
+    else builtins.trace "globals.nix missing, please add symlink" [];
+
+  # merge upstream sources with our own:
+  upstream-overlays = [
+      ( _: super: {
+
+      sourcePaths = (super.sourcePaths or {}) // sourcePaths;
+    })
+  ];
+
+  overlays =
+    local-overlays ++
+    globals ++
+    upstream-overlays;
+in
+  import sourcePaths.nixpkgs {
+    inherit overlays system crossSystem config;
+  }