diff --git a/modules/perSystem.nix b/modules/perSystem.nix
index 5632b9b..e70f5f6 100644
--- a/modules/perSystem.nix
+++ b/modules/perSystem.nix
@@ -49,7 +49,7 @@ in
     perSystem = system: { _module.args.system = system; };
     allSystems = genAttrs config.systems config.perSystem;
     # TODO: Sub-optimal error message. Get Nix to support a memoization primop, or get Nix Flakes to support systems properly or get Nix Flakes to add a name to flakes.
-    _module.args.getSystem = system: config.allSystems.${system} or builtins.trace "using non-memoized system ${system}" config.perSystem system;
+    _module.args.getSystem = system: config.allSystems.${system} or (builtins.trace "using non-memoized system ${system}" config.perSystem system);
   };
 
 }