diff --git a/nixos/modules/services/networking/nsd.nix b/nixos/modules/services/networking/nsd.nix
index 6af1dd736431..ccfd219620cf 100644
--- a/nixos/modules/services/networking/nsd.nix
+++ b/nixos/modules/services/networking/nsd.nix
@@ -118,8 +118,8 @@ let
   '';
 
   yesOrNo = b: if b then "yes" else "no";
-  maybeString = prefix: x: if x == null then "" else ''${prefix} "${s}"'';
-  maybeToString = prefix: x: if x == null then "" else ''${prefix} ${toString s}'';
+  maybeString = prefix: x: if x == null then "" else ''${prefix} "${x}"'';
+  maybeToString = prefix: x: if x == null then "" else ''${prefix} ${toString x}'';
   forEach = pre: l: concatMapStrings (x: pre + x + "\n") l;