diff --git a/scripts/wk/kit/ufd.py b/scripts/wk/kit/ufd.py
index fcf6fa23..114cd6f2 100644
--- a/scripts/wk/kit/ufd.py
+++ b/scripts/wk/kit/ufd.py
@@ -5,6 +5,7 @@ import logging
 import math
 import os
 import pathlib
+import re
 import shutil
 from subprocess import CalledProcessError
 
@@ -125,7 +126,7 @@ def build_ufd() -> None:
   if not args['--update']:
     ui.print_info('Prep UFD')
     try_print.run(
-      message='Zeroing first 64MiB...',
+      message='Zeroing first 1MiB...',
       function=zero_device,
       dev_path=ufd_dev,
       )
@@ -289,7 +290,7 @@ def confirm_selections(update=False) -> None:
 
 def copy_source(source, items, from_live=False, overwrite=False) -> None:
   """Copy source items to /mnt/UFD."""
-  is_image = not from_live and source.is_file()
+  is_image = not from_live and (source.is_file() or source.is_block_device())
   items_not_found = False
 
   # Mount source if necessary
@@ -474,6 +475,7 @@ def is_valid_path(path_obj, path_type) -> bool:
     valid_path = path_obj.is_file() and path_obj.suffix.lower() == '.img'
   elif path_type == 'ISO':
     valid_path = path_obj.is_file() and path_obj.suffix.lower() == '.iso'
+    valid_path = valid_path or re.match(r'^/dev/sr\d+$', str(path_obj))
   elif path_type == 'UFD':
     valid_path = path_obj.is_block_device()
 
@@ -676,12 +678,12 @@ def verify_ufd(dev_path) -> pathlib.Path:
 
 
 def zero_device(dev_path) -> None:
-  """Zero-out first 64MB of device."""
+  """Zero-out first 1MB of device."""
   cmd = [
     'sudo',
     'dd',
-    'bs=4M',
-    'count=16',
+    'bs=1M',
+    'count=1',
     'if=/dev/zero',
     f'of={dev_path}',
     ]