diff --git a/download_firefox_nightly.py b/download_firefox_nightly.py
index 1286eb8..db61914 100755
--- a/download_firefox_nightly.py
+++ b/download_firefox_nightly.py
@@ -139,7 +139,7 @@
   parser.add_option('-f', '--force', action='store_true',
                     help=('Force download even if the current nightly is '
                           'already downloaded.'))
-  parser.add_option('-c', '--clean-old-archives', action='store_true',
+  parser.add_option('-c', '--clean-old-firefox-archives', action='store_true',
                     help=('Clean old firefox archives; one will always be '
                           'kept as a fallback.'))
   options, _args = parser.parse_args()