Fix the count of datatypes.
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index d570228..a568d44 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -16,7 +16,7 @@
__name__ = '<doctest>'
This module implements high-performance container datatypes. Currently,
-there are three datatypes, :class:`Counter`, :class:`deque`, :class:`OrderedDict` and
+there are four datatypes, :class:`Counter`, :class:`deque`, :class:`OrderedDict` and
:class:`defaultdict`, and one datatype factory function, :func:`namedtuple`.
The specialized containers provided in this module provide alternatives