diff --git a/tools/download_file.py b/tools/download_file.py
index b705c1158d..26671f0f20 100755
--- a/tools/download_file.py
+++ b/tools/download_file.py
@@ -84,7 +84,7 @@ opts.add_option('--unsign', action='store_true')
 args, _ = opts.parse_args()
 
 root_dir = args.o
-while root_dir and root_dir != "/":
+while root_dir and path.dirname(root_dir) != root_dir:
   root_dir, n = path.split(root_dir)
   if n == 'WORKSPACE':
     break