diff --git a/docs/request_response.txt b/docs/request_response.txt
index 867464226a..1eef41659a 100644
--- a/docs/request_response.txt
+++ b/docs/request_response.txt
@@ -183,6 +183,9 @@ subclass of dictionary. Exceptions are outlined here:
 
     * ``__getitem__(key)`` -- Returns the value for the given key. If the key
       has more than one value, ``__getitem__()`` returns the last value.
+      Raises ``django.utils.datastructure.MultiValueDictKeyError`` if the key
+      does not exist (fortunately, this is a subclass of Python's standard
+      ``KeyError``, so you can stick to catching ``KeyError``).
 
     * ``__setitem__(key, value)`` -- Sets the given key to ``[value]``
       (a Python list whose single element is ``value``). Note that this, as