diff --git a/django/middleware/common.py b/django/middleware/common.py
index d63b71fed7..4f060b8590 100644
--- a/django/middleware/common.py
+++ b/django/middleware/common.py
@@ -64,8 +64,9 @@ class CommonMiddleware(object):
                 is_internal = referer and (domain in referer)
                 path = request.get_full_path()
                 if referer and not _is_ignorable_404(path) and (is_internal or '?' not in referer):
+                    ua = request.META.get('HTTP_USER_AGENT','<none>')
                     mail_managers("Broken %slink on %s" % ((is_internal and 'INTERNAL ' or ''), domain),
-                        "Referrer: %s\nRequested URL: %s\n" % (referer, request.get_full_path()))
+                        "Referrer: %s\nRequested URL: %s\nUser Agent: %s\n" % (referer, request.get_full_path(), ua))
                 return response
 
         # Use ETags, if requested.