diff --git a/flake-module.nix b/flake-module.nix
index a23f9b7a..ab7e59e0 100644
--- a/flake-module.nix
+++ b/flake-module.nix
@@ -169,9 +169,18 @@ in
                 localPackagesOverlay = self: _:
                   let
                     fromSdist = self.buildFromCabalSdist or (builtins.trace "Your version of Nixpkgs does not support hs.buildFromCabalSdist yet." (pkg: pkg));
+                    filterSrc = name: src: lib.cleanSourceWith { inherit src name; filter = path: type: true; };
                   in
                   lib.mapAttrs
-                    (name: value: fromSdist (self.callCabal2nix name value.root { }))
+                    (name: value:
+                      let
+                        # callCabal2nix does not need a filtered source. It will
+                        # only pick out the cabal and/or hpack file.
+                        pkgProto = self.callCabal2nix name value.root { };
+                        pkgFiltered = pkgs.haskell.lib.overrideSrc pkgProto {
+                          src = filterSrc name value.root;
+                        };
+                      in fromSdist pkgFiltered)
                     cfg.packages;
                 finalOverlay =
                   pkgs.lib.composeManyExtensions