diff --git a/installer/preinstall.d/08-crypttab.sh b/installer/preinstall.d/08-crypttab.sh
index 31fd1e6..920d3b4 100755
--- a/installer/preinstall.d/08-crypttab.sh
+++ b/installer/preinstall.d/08-crypttab.sh
@@ -4,20 +4,19 @@
 
 [ -f /tmp/fstab ] || exit 0
 
-for device in $(find /dev/ -name 'dm-*' -type b);
+for device in $(findmnt -neo SOURCE -F /tmp/fstab);
 do
-       uuid=$(blkid -o value -s UUID "$device")
-       fgrep "$uuid" "/tmp/fstab" &> /dev/null || continue
+       # filter out non-luks devices
+       MAJMIN="$(findmnt $device -rno MAJ:MIN)"
+       device_luks="/dev/"$(ls -1 "/sys/dev/block/$MAJMIN/slaves/")
+       [ "$(blkid -o value -s TYPE "$device_luks")" = "crypto_LUKS" ] || continue
+
        # we should add luks feature to initrd if / is placed on luks
        # or create /etc/crypttab otherwise
-       if grep -qe ".*$uuid.*[^[:alnum:]]/[^[:alnum:]]" "/tmp/fstab"; then
+       if [ "$(findmnt $device -no TARGET -F /tmp/fstab)" = "/" ]; then
                echo 'FEATURES += luks' >> $destdir/etc/initrd.mk
-               exit 0
        fi
 
-       device_luks="/dev/"$(ls "/sys/block/$(basename "$device")/slaves/")
-       [ "$(blkid -o value -s TYPE "$device_luks")" = "crypto_LUKS" ] || continue
-
        luks_uuid=$(blkid -o value -s UUID "$device_luks")
 
        [ -r "$destdir/etc/crypttab" ] && fgrep "$luks_uuid" "$destdir/etc/crypttab" &> /dev/null && continue