diff --git a/configuration.nix b/configuration.nix
index b882672..ae93c10 100644
--- a/configuration.nix
+++ b/configuration.nix
@@ -21,6 +21,7 @@
     nixpkgs.config.allowUnfree = true;
     nix.gc.automatic = true;
     nix.gc.dates = "03:15";
+    nix.gc.options = "--delete-older-than 15d";
 
     # This value determines the NixOS release with which your system is to be
     # compatible, in order to avoid breaking some software such as database