diff --git a/Doc/library/logging.rst b/Doc/library/logging.rst
index 53ba9a9..d458bfe 100644
--- a/Doc/library/logging.rst
+++ b/Doc/library/logging.rst
@@ -1359,6 +1359,9 @@
 :class:`Lock` class from this module to serialize access to the file from
 your processes. The existing :class:`FileHandler` and subclasses do not make
 use of :mod:`multiprocessing` at present, though they may do so in the future.
+Note that at present, the :mod:`multiprocessing` module does not provide
+working lock functionality on all platforms (see
+http://bugs.python.org/issue3770).
 
 .. _network-logging: