diff --git a/nixos/tests/os-prober.nix b/nixos/tests/os-prober.nix
index a7b955d4472..c1e29b0f68b 100644
--- a/nixos/tests/os-prober.nix
+++ b/nixos/tests/os-prober.nix
@@ -53,12 +53,12 @@ let
   };
   # /etc/nixos/configuration.nix for the vm
   configFile = pkgs.writeText "configuration.nix"  ''
-    {config, pkgs, ...}: ({
+    {config, pkgs, lib, ...}: ({
     imports =
           [ ./hardware-configuration.nix
             <nixpkgs/nixos/modules/testing/test-instrumentation.nix>
           ];
-    } // pkgs.lib.importJSON ${
+    } // lib.importJSON ${
       pkgs.writeText "simpleConfig.json" (builtins.toJSON simpleConfig)
     })
   '';
@@ -114,7 +114,7 @@ in {
         "${configFile}",
         "/etc/nixos/configuration.nix",
     )
-    machine.succeed("nixos-rebuild boot >&2")
+    machine.succeed("nixos-rebuild boot --show-trace >&2")
 
     machine.succeed("egrep 'menuentry.*debian' /boot/grub/grub.cfg")
   '';