diff --git a/flake.nix b/flake.nix
index 9a50704..63928f8 100644
--- a/flake.nix
+++ b/flake.nix
@@ -23,11 +23,12 @@
         in
           (type == "regular") && (builtins.elem bname names);
 
-        npSrc = pkgs.lib.cleanSourceWith {
-          filter = name: type:
-            (type == "directory") || (naiveFilter ["package.json" "yarn.lock"] name type);
-          src = ./.;
-        };
+        mkNpSrc = src:
+          pkgs.lib.cleanSourceWith {
+            inherit src;
+            filter = name: type:
+              (type == "directory") || (naiveFilter ["package.json" "yarn.lock"] name type);
+          };
         mimeTypes = pkgs.concatTextFile {
           name = "mime.types";
           files = [./mime.types];