diff --git a/pep-3154.txt b/pep-3154.txt
index 9ed7b7f5c..a7a2249c0 100644
--- a/pep-3154.txt
+++ b/pep-3154.txt
@@ -67,12 +67,20 @@ Currently, classes whose __new__ mandates the use of keyword-only arguments
 can not be pickled (or, rather, unpickled) [3]_.  Both a new special method
 (``__getnewargs_ex__`` ?) and a new opcode (NEWOBJEX ?) are needed.
 
+Serializing more callable objects
+---------------------------------
+
+Currently, only module-global functions are serializable.  Multiprocessing
+has custom support for pickling other callables such as bound methods [4]_.
+This support could be folded in the protocol, and made more efficient
+through a new GETATTR opcode.
+
 Serializing "pseudo-global" objects
 -----------------------------------
 
 Objects which are not module-global, but should be treated in a similar
-fashion -- such as methods [4]_ or nested classes -- cannot currently be
-pickled (or, rather, unpickled) because the pickle protocol does not
+fashion -- such as unbound methods [5]_ or nested classes -- cannot currently
+be pickled (or, rather, unpickled) because the pickle protocol does not
 correctly specify how to retrieve them.  One solution would be through the
 adjunction of a ``__namespace__`` (or ``__qualname__``) to all class and
 function objects, specifying the full "path" by which they can be retrieved.
@@ -119,7 +127,10 @@ References
 .. [3] "pickle/copyreg doesn't support keyword only arguments in __new__":
    http://bugs.python.org/issue4727
 
-.. [4] "pickle should support methods":
+.. [4] Lib/multiprocessing/forking.py:
+   http://hg.python.org/cpython/file/baea9f5f973c/Lib/multiprocessing/forking.py#l54
+
+.. [5] "pickle should support methods":
    http://bugs.python.org/issue9276
 
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