diff --git a/setup.py b/setup.py
index 76b22c40f929d109717a27be545a1f6c8f281e00..fcba3027baee3169ba0fd74c3841bb757672eeee 100755
--- a/setup.py
+++ b/setup.py
@@ -65,7 +65,8 @@ class CleanCmd(Command):
   def run(self):
     # Configure for this project.
     suffixes2del = ['MANIFEST', '.pyc', 'chkcrontabc']
-    dirs2del = ['./build', './dist', './.tox', './.coverage']
+    dirs2del = ['./build', './dist', './.tox', './.coverage',
+                './__pycache__']
     dirs2ign = ['./.git']
     # End config.
     doomed = set()