diff --git a/xterm/shellserver.pl b/xterm/shellserver.pl
index 513d980ba..99ce7d07c 100755
--- a/xterm/shellserver.pl
+++ b/xterm/shellserver.pl
@@ -4,6 +4,7 @@
 use strict;
 use warnings;
 no warnings 'uninitialized';
+no warnings 'once';
 use lib ("$ENV{'PERLLIB'}/vendor_perl");
 use Net::WebSocket::Server;
 use IO::Socket::INET;