document default value for fillvalue
diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index 5d3593e..13d3147 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -368,9 +368,10 @@
except IndexError:
pass
- If one of the iterables is potentially infinite, then the :func:`izip_longest`
- function should be wrapped with something that limits the number of calls (for
- example :func:`islice` or :func:`takewhile`).
+ If one of the iterables is potentially infinite, then the
+ :func:`izip_longest` function should be wrapped with something that limits
+ the number of calls (for example :func:`islice` or :func:`takewhile`). If
+ not specified, *fillvalue* defaults to ``None``.
.. versionadded:: 2.6