diff --git a/common.nix b/common.nix
index 781ecec..d4762da 100644
--- a/common.nix
+++ b/common.nix
@@ -29,6 +29,12 @@
       ];
       auto-optimise-store = true;
     };
+    gc = {
+      automatic = true;
+      dates = "weekly";
+      options = "--delete-older-than 30d";
+      persistent = true;
+    };
   };
 
   system.configurationRevision = lib.mkIf (inputs.self ? rev) inputs.self.rev;