diff --git a/src/system.nix b/src/system.nix
index 3899718..9bc3833 100644
--- a/src/system.nix
+++ b/src/system.nix
@@ -18,6 +18,8 @@
       flake-registry = "${registry}/flake-registry.json";
       extra-sandbox-paths = [ "/homeless-shelter/.ccache" ];
     };
+    gc.automatic = true;
+    gc.options = "--delete-older-than 7d";
   };
 
   programs.ccache = {