diff --git a/docs/conf.py b/docs/conf.py
index 3e4690a0f..2f25c9a7b 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -21,6 +21,7 @@ import mock
 
 
 # http://docs.readthedocs.org/en/latest/faq.html#i-get-import-errors-on-libraries-that-depend-on-c-modules
+# c.f. #262
 sys.modules.update(
     (mod_name, mock.MagicMock()) for mod_name in ['augeas', 'M2Crypto'])