diff --git a/post-debootstrap-installer.sh b/post-debootstrap-installer.sh
index d00d8da..7f1b2dd 100755
--- a/post-debootstrap-installer.sh
+++ b/post-debootstrap-installer.sh
@@ -38,9 +38,17 @@ cat /hardware-setup/authorized_keys/* > /etc/dropbear-initramfs/authorized_keys
 apt-get -y install linux-image-amd64
 
 # install grub
-apt-get -y install grub-efi-amd64
-update-grub
-grub-install --target=x86_64-efi --efi-directory=/boot/efi/ --bootloader-id=GRUB
+if [ -d /sys/firmware/efi ]; then
+    apt-get -y install grub-efi-amd64
+    update-grub
+    grub-install
+else
+    apt-get -y install grub-pc
+    update-grub
+
+    root_disk="/dev/$(lsblk -no pkname $(cryptsetup status root-unlocked | grep device | perl -pe 's#.*device.* (.*)#$1#') | sort | head -n1)"
+    grub-install "$root_disk"
+fi
 
 # edit uuids in fstab
 root_uuid=$(blkid --output value "/dev/mapper/root-unlocked" | head -n1)