diff --git a/util/grub-install.in b/util/grub-install.in
index b0823642a..0956c0902 100644
--- a/util/grub-install.in
+++ b/util/grub-install.in
@@ -498,6 +498,7 @@ if [ "x${devabstraction_module}" = "x" ] ; then
     grub_drive="`$grub_probe --target=drive --device ${grub_device}`" || exit 1
 
     # Strip partition number
+    grub_partition="`echo ${grub_drive} | sed -e 's/^[^,]*,//; s/)$//'`"
     grub_drive="`echo ${grub_drive} | sed -e s/,[a-z0-9,]*//g`"
     if [ "$disk_module" = ata ] ; then
         # generic method (used on coreboot and ata mod)
@@ -520,6 +521,10 @@ if [ "x${devabstraction_module}" = "x" ] ; then
 	echo 'set prefix=($root)'"${relative_grubdir}" >> ${grubdir}/load.cfg
 	config_opt="-c ${grubdir}/load.cfg "
         modules="$modules search_fs_uuid"
+    elif [ "x$platform" = xefi ]; then
+        # No grub-setup, so we need to hardcode the partition number in the
+        # core image's prefix.
+        prefix_drive="(,$grub_partition)"
     fi
 else
     prefix_drive=`$grub_probe --target=drive --device ${grub_device}` || exit 1