diff --git a/hosts/silicium/system/nix/default.nix b/hosts/silicium/system/nix/default.nix
index 5fdb0ff..bdaeab6 100644
--- a/hosts/silicium/system/nix/default.nix
+++ b/hosts/silicium/system/nix/default.nix
@@ -18,7 +18,7 @@
   nix.settings.auto-optimise-store = true;
   nix.optimise = {
     automatic = true;
-    dates = "12:00";
+    dates = ["12:00"];
   };
 
   # garbage collection