diff --git a/nixos/modules/services/continuous-integration/hydra/default.nix b/nixos/modules/services/continuous-integration/hydra/default.nix
index 54bbe69703f9..b1d44e67658b 100644
--- a/nixos/modules/services/continuous-integration/hydra/default.nix
+++ b/nixos/modules/services/continuous-integration/hydra/default.nix
@@ -39,7 +39,7 @@ let
 
   hydra-package =
   let
-    makeWrapperArgs = concatStringsSep " " (mapAttrsToList (key: value: "--set \"${key}\" \"${value}\"") hydraEnv);
+    makeWrapperArgs = concatStringsSep " " (mapAttrsToList (key: value: "--set-default \"${key}\" \"${value}\"") hydraEnv);
   in pkgs.buildEnv rec {
     name = "hydra-env";
     nativeBuildInputs = [ pkgs.makeWrapper ];