diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index d5702289c3e..a568d44f6ad 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