diff --git a/script/lib/util.py b/script/lib/util.py
index af71468652d5..7c890bf87c7c 100644
--- a/script/lib/util.py
+++ b/script/lib/util.py
@@ -70,7 +70,7 @@ def make_zip(zip_file_path, files, dirs):
     files += dirs
     subprocess.check_call(['zip', '-r', '-y', zip_file_path] + files)
   else:
-    zip_file = zipfile.ZipFile(zip_file_path, "w")
+    zip_file = zipfile.ZipFile(zip_file_path, "w", zipfile.ZIP_DEFLATED)
     for filename in files:
       zip_file.write(filename, filename)
     for dirname in dirs: