diff --git a/Doc/library/asyncio-stream.rst b/Doc/library/asyncio-stream.rst
index 3fe7ac7..27b5205 100644
--- a/Doc/library/asyncio-stream.rst
+++ b/Doc/library/asyncio-stream.rst
@@ -146,10 +146,12 @@
 StreamReader
 ============
 
-.. class:: StreamReader(limit=None, loop=None)
+.. class:: StreamReader(limit=_DEFAULT_LIMIT, loop=None)
 
    This class is :ref:`not thread safe <asyncio-multithreading>`.
 
+   The *limit* argument's default value is set to _DEFAULT_LIMIT which is 2**16 (64 KiB)
+
    .. method:: exception()
 
       Get the exception.