diff --git a/Lib/asyncio/futures.py b/Lib/asyncio/futures.py
index 91ea170..4edd2e5 100644
--- a/Lib/asyncio/futures.py
+++ b/Lib/asyncio/futures.py
@@ -169,6 +169,9 @@
             res += '<{}>'.format(self._state)
         return res
 
+    # On Python 3.3 or older, objects with a destructor part of a reference
+    # cycle are never destroyed. It's not more the case on Python 3.4 thanks to
+    # the PEP 442.
     if _PY34:
         def __del__(self):
             if not self._log_traceback: