diff --git a/nixos/modules/system/boot/loader/grub/grub.nix b/nixos/modules/system/boot/loader/grub/grub.nix
index c790e05f51b..1fb2e20949a 100644
--- a/nixos/modules/system/boot/loader/grub/grub.nix
+++ b/nixos/modules/system/boot/loader/grub/grub.nix
@@ -354,7 +354,7 @@ in
         export PERL5LIB=${makePerlPath (with pkgs.perlPackages; [ FileSlurp XMLLibXML XMLSAX ListCompare ])}
         ${optionalString cfg.enableCryptodisk "export GRUB_ENABLE_CRYPTODISK=y"}
       '' + flip concatMapStrings cfg.mirroredBoots (args: ''
-        ${pkgs.perl}/bin/perl ${./install-grub.pl} ${grubConfig args}
+        ${pkgs.perl}/bin/perl ${./install-grub.pl} ${grubConfig args} $@
       ''));
 
       system.build.grub = grub;
diff --git a/nixos/modules/system/boot/loader/grub/install-grub.pl b/nixos/modules/system/boot/loader/grub/install-grub.pl
index a0384d23f82..3ca30b58023 100644
--- a/nixos/modules/system/boot/loader/grub/install-grub.pl
+++ b/nixos/modules/system/boot/loader/grub/install-grub.pl
@@ -11,7 +11,7 @@ require List::Compare;
 use POSIX;
 use Cwd;
 
-my $defaultConfig = $ARGV[0] or die;
+my $defaultConfig = $ARGV[1] or die;
 
 my $dom = XML::LibXML->load_xml(location => $ARGV[0]);