diff --git a/pelican/utils.py b/pelican/utils.py
index d8a19e4b..23c6fe1c 100644
--- a/pelican/utils.py
+++ b/pelican/utils.py
@@ -758,7 +758,6 @@ def order_content(content_list, order_by='slug'):
 
 
 def wait_for_changes(settings_file, reader_class, settings):
-    new_extensions = set(reader_class(settings).extensions)
     content_path = settings.get('PATH', '')
     theme_path = settings.get('THEME', '')
     ignore_files = set(settings.get('IGNORE_FILES', []))