diff --git a/docs/ref/class-based-views.txt b/docs/ref/class-based-views.txt
index 3c7f70f..b89416a 100644
--- a/docs/ref/class-based-views.txt
+++ b/docs/ref/class-based-views.txt
@@ -479,6 +479,12 @@ FormMixin
         provide an implementation of :meth:`.form_valid` and
         :meth:`.form_invalid`.
 
+    .. admonition:: Changed in 1.4
+
+        Django 1.3 treated :attr:`.initial` as a class variable, so it
+        was shared between all :class:`FormMixin` instances. Later
+        versions treat intial as an instance variable.
+
 ModelFormMixin
 ~~~~~~~~~~~~~~
 .. class:: ModelFormMixin()