diff --git a/nikola/__main__.py b/nikola/__main__.py
index bb8c35295a..2b0d3aef7d 100644
--- a/nikola/__main__.py
+++ b/nikola/__main__.py
@@ -244,13 +244,14 @@ def __init__(self, *args, **kw):
 class Clean(DoitClean):
     """Clean site, including the cache directory."""
 
-    def clean_tasks(self, tasks, dryrun):
+    # The unseemly *a is because this API changed between doit 0.30.1 and 0.31
+    def clean_tasks(self, tasks, dryrun, *a):
         """Clean tasks."""
         if not dryrun and config:
             cache_folder = config.get('CACHE_FOLDER', 'cache')
             if os.path.exists(cache_folder):
                 shutil.rmtree(cache_folder)
-        return super(Clean, self).clean_tasks(tasks, dryrun)
+        return super(Clean, self).clean_tasks(tasks, dryrun, *a)
 
 
 # Nikola has its own "auto" commands that uses livereload.