diff --git a/nixos/modules/system/boot/loader/grub/grub.nix b/nixos/modules/system/boot/loader/grub/grub.nix
index 2e497ff9f2c4..42da65857221 100644
--- a/nixos/modules/system/boot/loader/grub/grub.nix
+++ b/nixos/modules/system/boot/loader/grub/grub.nix
@@ -385,8 +385,9 @@ in
       };
 
       default = mkOption {
-        default = 0;
-        type = types.int;
+        default = "0";
+        type = types.either types.int types.str;
+        apply = toString;
         description = ''
           Index of the default menu item to be booted.
         '';
diff --git a/nixos/modules/system/boot/loader/grub/install-grub.pl b/nixos/modules/system/boot/loader/grub/install-grub.pl
index 872261d0edfa..d1ff6e6bf525 100644
--- a/nixos/modules/system/boot/loader/grub/install-grub.pl
+++ b/nixos/modules/system/boot/loader/grub/install-grub.pl
@@ -54,7 +54,7 @@ my $splashImage = get("splashImage");
 my $configurationLimit = int(get("configurationLimit"));
 my $copyKernels = get("copyKernels") eq "true";
 my $timeout = int(get("timeout"));
-my $defaultEntry = int(get("default"));
+my $defaultEntry = get("default");
 my $fsIdentifier = get("fsIdentifier");
 my $grubEfi = get("grubEfi");
 my $grubTargetEfi = get("grubTargetEfi");