diff --git a/default.nix b/default.nix
index 729c5d87..c6d15dab 100644
--- a/default.nix
+++ b/default.nix
@@ -1,6 +1,6 @@
-{
-  sources ? import ./npins,
-}:
+let
+  sources = import ./npins;
+in
 {
   # for repl sessions
   inherit sources;
diff --git a/shell.nix b/shell.nix
index 1fc63cf4..31c91133 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,8 +1,11 @@
+let
+  sources = import ./npins;
+in
 {
-  sources ? import ./npins,
   pkgs ? import sources.nixpkgs {
     overlays = map import [
       ./nix/overlays/disko.nix
+      ./nix/overlays/npins.nix
     ];
   },
   withGHC ? false,