Record version added as 3.1.
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index ef1bca2..1a23fca 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -367,7 +367,7 @@
 
       Maximum size of a deque or *None* if unbounded.
 
-      .. versionadded:: 2.7
+      .. versionadded:: 3.1
 
 
 In addition to the above, deques support iteration, pickling, ``len(d)``,