diff --git a/modules/drumknotty.nix b/modules/drumknotty.nix
index d747af6..8e8e142 100644
--- a/modules/drumknotty.nix
+++ b/modules/drumknotty.nix
@@ -125,7 +125,7 @@ in
 
         services.drumknotty.dibblerSettings = {
           limits = {
-            low_credit_warning_limit = lib.mkDefault - 100;
+            low_credit_warning_limit = lib.mkDefault (-100);
             user_recent_transaction_limit = lib.mkDefault 100;
           };