diff --git a/doc/management.txt b/doc/management.txt
index c7eb7ff..4418328 100644
--- a/doc/management.txt
+++ b/doc/management.txt
@@ -199,6 +199,10 @@
     in foreground and to show incoming and outgoing events. It must never be
     used in an init script.
 
+  -dD : enable diagnostic mode. This mode will output extra warnings about
+    suspicious configuration statements. This will never prevent startup even in
+    "zero-warning" mode nor change the exit status code.
+
   -dG : disable use of getaddrinfo() to resolve host names into addresses. It
     can be used when suspecting that getaddrinfo() doesn't work as expected.
     This option was made available because many bogus implementations of