diff --git a/base.nix b/base.nix
index d34597e..4d723a6 100644
--- a/base.nix
+++ b/base.nix
@@ -38,6 +38,9 @@ in {
     boot.kernelParams = [ "console=tty0" "console=ttyS0,115200"];
     services.qemuGuest.enable = true;
 
+    nix.gc.automatic = true;
+    nix.gc.options = "--delete-older-than 30d";
+
     system.autoUpgrade.enable = true;
     system.autoUpgrade.allowReboot = true;