diff --git a/modules/generic.nix b/modules/generic.nix
index e6d4090..f418476 100644
--- a/modules/generic.nix
+++ b/modules/generic.nix
@@ -118,8 +118,8 @@ in
   #virtualisation.podman.autoPrune.enable = config.virtualisation.podman.enable;
 
   nix.gc = {
-    automatic = true;
-    options = "--delete-older-than 2d";
+    automatic = lib.mkDefault true;
+    options = lib.mkDefault "--delete-older-than 2d";
   };
 
   boot.cleanTmpDir = true;