diff --git a/nixos/tests/installer.nix b/nixos/tests/installer.nix
index c5abd458ec9a..8d1bfa96d03d 100644
--- a/nixos/tests/installer.nix
+++ b/nixos/tests/installer.nix
@@ -29,7 +29,7 @@ let
             boot.loader.grub.splashImage = null;
           ''}
 
-          boot.loader.grub.extraConfig = "serial; terminal_output.serial";
+          boot.loader.grub.extraConfig = "serial; terminal_output serial";
           ${if grubUseEfi then ''
             boot.loader.grub.device = "nodev";
             boot.loader.grub.efiSupport = true;