diff --git a/Lib/io.py b/Lib/io.py
index 2283276..1438493 100644
--- a/Lib/io.py
+++ b/Lib/io.py
@@ -68,15 +68,16 @@
 # version however.
 class IOBase(_io._IOBase):
     __metaclass__ = abc.ABCMeta
+    __doc__ = _io._IOBase.__doc__
 
 class RawIOBase(_io._RawIOBase, IOBase):
-    pass
+    __doc__ = _io._RawIOBase.__doc__
 
 class BufferedIOBase(_io._BufferedIOBase, IOBase):
-    pass
+    __doc__ = _io._BufferedIOBase.__doc__
 
 class TextIOBase(_io._TextIOBase, IOBase):
-    pass
+    __doc__ = _io._TextIOBase.__doc__
 
 RawIOBase.register(FileIO)