diff --git a/nixos/common/modules/nixos.nix b/nixos/common/modules/nixos.nix
index a91fdae2..2a3f9ca8 100644
--- a/nixos/common/modules/nixos.nix
+++ b/nixos/common/modules/nixos.nix
@@ -4,7 +4,7 @@
 
   nix.optimise = {
     automatic = true;
-    dates = "daily";
+    dates = ["daily"];
   };
 
   # Garbage collection -- Keep the system clean