diff --git a/flake.nix b/flake.nix
index 119fb5a..96f3740 100644
--- a/flake.nix
+++ b/flake.nix
@@ -16,7 +16,13 @@
       };
 
       packages.${system} = let
-        src = lib.cleanSource ./.;
+        src = lib.fileset.toSource {
+          root = ./.;
+          fileset = lib.fileset.unions [
+            ./Makefile
+            ./src
+          ];
+        };
       in {
         default = self.packages.${system}.wamf;
         wamf = pkgs.callPackage ./nix/package.nix { inherit src; };