diff -r 3ae2cd85a908 Doc/c-api/dict.rst
--- a/Doc/c-api/dict.rst	Sun Mar 09 11:18:16 2014 +0100
+++ b/Doc/c-api/dict.rst	Tue Mar 25 13:43:45 2014 +0530
@@ -201,8 +201,8 @@
 
 .. c:function:: int PyDict_Update(PyObject *a, PyObject *b)
 
-   This is the same as ``PyDict_Merge(a, b, 1)`` in C, or ``a.update(b)`` in
-   Python.  Return ``0`` on success or ``-1`` if an exception was raised.
+   This is the same as ``PyDict_Merge(a, b, 1)`` in C, and is similar to ``a.update(b)`` in
+   Python except that ``PyDict_Update`` doesn't fall back to the iterating over a sequence of key value pairs if the second argument has no "keys" attribute.  Return ``0`` on success or ``-1`` if an exception was raised.
 
 
 .. c:function:: int PyDict_MergeFromSeq2(PyObject *a, PyObject *seq2, int override)