diff --git a/nixos/lib/testing/driver.nix b/nixos/lib/testing/driver.nix
index 3b082140e935..7421c25b2fbd 100644
--- a/nixos/lib/testing/driver.nix
+++ b/nixos/lib/testing/driver.nix
@@ -36,7 +36,7 @@ let
       theOnlyMachine =
         let
           exactlyOneMachine = lib.length (lib.attrValues config.nodes) == 1;
-          allMachineNames = map (c: c.system.name) (lib.attrValues config.allMachines);
+          allMachineNames = lib.attrNames config.allMachines;
         in
         lib.optional (exactlyOneMachine && !lib.elem "machine" allMachineNames) "machine";