diff --git a/src/patches/grub-0.97_grub-install_virtio.patch b/src/patches/grub-0.97_grub-install_virtio.patch
index 432e0f145..190536383 100644
--- a/src/patches/grub-0.97_grub-install_virtio.patch
+++ b/src/patches/grub-0.97_grub-install_virtio.patch
@@ -21,7 +21,7 @@ diff -Naur grub-0.97.org/util/grub-install.in grub-0.97/util/grub-install.in
      :
  else
 +
-+  tmp_disk=`echo "$1" | grep "/dev/vd"`
++  tmp_disk=`echo "$install_device" | grep "/dev/vd"`
 +  if test "x$tmp_disk" = x; then
 +
      # Create a safe temporary file.