diff --git a/overlay.nix b/overlay.nix
index 73e64a2..e6af158 100644
--- a/overlay.nix
+++ b/overlay.nix
@@ -4,14 +4,17 @@ let
     mapAttrs'
     removeSuffix
     ;
+  mkGeneralOverlay =
+    dir: self: super:
+    mapAttrs' (name: _: {
+      value = self.callPackage (dir + "/${name}") { };
+      name = removeSuffix ".nix" name;
+    }) (builtins.readDir dir);
 in
-mapAttrs' (name: _: {
-  value = final.callPackage ./pkgs/${name} { };
-  name = removeSuffix ".nix" name;
-}) (builtins.readDir ./pkgs)
+mkGeneralOverlay ./pkgs final prev
 // {
   formats = prev.formats // {
     xml = import ./xml.nix { pkgs = final; };
   };
-  pythonPackagesExtensions = prev.pythonPackagesExtensions ++ [ (import ./python_overlay.nix) ];
+  pythonPackagesExtensions = prev.pythonPackagesExtensions ++ [ (mkGeneralOverlay ./python-pkgs) ];
 }
diff --git a/python_overlay.nix b/python_overlay.nix
deleted file mode 100644
index 79af2dd..0000000
--- a/python_overlay.nix
+++ /dev/null
@@ -1,11 +0,0 @@
-final: prev:
-let
-  inherit (prev.lib)
-    mapAttrs'
-    removeSuffix
-    ;
-in
-mapAttrs' (name: _: {
-  value = final.callPackage ./python-pkgs/${name} { };
-  name = removeSuffix ".nix" name;
-}) (builtins.readDir ./python-pkgs)