diff --git a/scripts/mosh b/scripts/mosh
index 737500d..d5ce42c 100755
--- a/scripts/mosh
+++ b/scripts/mosh
@@ -263,7 +263,7 @@ if ( $pid == 0 ) { # child
 	die "Bad MOSH CONNECT string: $_\n";
       }
     } else {
-      if ( $port_request =~ m{:} and m{Bad UDP port} ) {
+      if ( defined $port_request and $port_request =~ m{:} and m{Bad UDP port} ) {
 	$bad_udp_port_warning = 1;
       }
       print "$_\n";