diff --git a/bin/nsupdate/nsupdate.rst b/bin/nsupdate/nsupdate.rst
index 8ce42b2f66..d2f21fd2c5 100644
--- a/bin/nsupdate/nsupdate.rst
+++ b/bin/nsupdate/nsupdate.rst
@@ -262,6 +262,8 @@ The command formats and their meanings are as follows:
    update requests are sent. If no port number is specified, the default
    DNS port number of 53 is used.
 
+   .. note:: This command has no effect when GSS-TSIG is in use.
+
 ``local address port``
    This command sends all dynamic update requests using the local ``address``. When
    no local statement is provided, :program:`nsupdate` sends updates using
diff --git a/doc/man/nsupdate.1in b/doc/man/nsupdate.1in
index 621d1e65e7..4fc6406912 100644
--- a/doc/man/nsupdate.1in
+++ b/doc/man/nsupdate.1in
@@ -295,6 +295,13 @@ zone\(aqs SOA record identify the primary server for that zone.
 \fBport\fP is the port number on \fBservername\fP where the dynamic
 update requests are sent. If no port number is specified, the default
 DNS port number of 53 is used.
+.sp
+\fBNOTE:\fP
+.INDENT 7.0
+.INDENT 3.5
+This command has no effect when GSS\-TSIG is in use.
+.UNINDENT
+.UNINDENT
 .TP
 .B \fBlocal address port\fP
 This command sends all dynamic update requests using the local \fBaddress\fP\&. When