diff --git a/nix-conf/machines/djmuk2/configuration.nix b/nix-conf/machines/djmuk2/configuration.nix
index b8697e9..8d679ac 100644
--- a/nix-conf/machines/djmuk2/configuration.nix
+++ b/nix-conf/machines/djmuk2/configuration.nix
@@ -69,6 +69,8 @@
    ];
 
    nix.settings.trusted-users = [ "root" "djm" ];
+   nix.optimise.automatic = true;
+   nix.optimise.dates = [ "03:00" ];
 
    i18n.defaultLocale = "en_GB.UTF-8";
 
diff --git a/nix-conf/machines/edrahil/configuration.nix b/nix-conf/machines/edrahil/configuration.nix
index cd9a962..2ef4c9d 100644
--- a/nix-conf/machines/edrahil/configuration.nix
+++ b/nix-conf/machines/edrahil/configuration.nix
@@ -73,6 +73,8 @@
    ];
 
    nix.settings.trusted-users = [ "root" "djm" ];
+   nix.optimise.automatic = true;
+   nix.optimise.dates = [ "03:00" ];
 
    i18n.defaultLocale = "en_GB.UTF-8";