Index: django/core/formfields.py
===================================================================
--- django/core/formfields.py	(revision 1593)
+++ django/core/formfields.py	(working copy)
@@ -398,9 +398,15 @@
         checked_html = ''
         if data or (data is '' and self.checked_by_default):
             checked_html = ' checked="checked"'
-        return '<input type="checkbox" id="%s" class="v%s" name="%s"%s />' % \
-            (self.get_id(), self.__class__.__name__,
-            self.field_name, checked_html)
+        html_values = { 
+            'id' : self.get_id(),
+            'class_name' : self.__class__.__name__,
+            'name' : self.field_name,
+            'checked_html' : checked_html }
+        html_output = []
+        html_output.append('<input type="checkbox" id="%(id)s" class="v%(class_name)s" name="%(name)s"%(checked_html)s />')
+        html_output.append('<input type="hidden" id="%(id)s_check" name="%(name)s_check" value="1"/>')
+        return ''.join(html_output) % html_values
 
     def html2python(data):
         "Convert value from browser ('on' or '') to a Python boolean"