diff --git a/overlays/nix.nix b/overlays/nix.nix
index 317f275..2d5ee5d 100644
--- a/overlays/nix.nix
+++ b/overlays/nix.nix
@@ -1,13 +1,13 @@
 # TODO: remove after upstream fixes https://github.com/NixOS/nix/issues/5728
 self: super: {
-  nixUnstable = super.nixUnstable.overrideAttrs(_: rec {
+  nixUnstable = super.nixUnstable.override rec {
     version = "2.5${suffix}";
-    suffix = "pre20211007_${self.lib.substring 0 7 src.rev}";
-    src = self.fetchFromGitHub {
+    suffix = "pre20211007_${super.lib.substring 0 7 src.rev}";
+    src = super.fetchFromGitHub {
       owner = "NixOS";
       repo = "nix";
       rev = "844dd901a7debe8b03ec93a7f717b6c4038dc572";
       sha256 = "sha256-fe1B4lXkS6/UfpO0rJHwLC06zhOPrdSh4s9PmQ1JgPo=";
     };
-  });
+  };
 }