diff --git a/modules/common/default.nix b/modules/common/default.nix
index 1937bff..eb7c0b1 100644
--- a/modules/common/default.nix
+++ b/modules/common/default.nix
@@ -34,7 +34,7 @@ in
       gc = {
         automatic = true;
         dates = "weekly";
-        options = "--delete-older-than 30d";
+        options = lib.mkDefault "--delete-older-than 30d";
       };
       settings.experimental-features = [
         "nix-command"