diff --git a/xCAT-server/lib/xcat/plugins/dhcp.pm b/xCAT-server/lib/xcat/plugins/dhcp.pm
index e9b27f350..d04eef543 100644
--- a/xCAT-server/lib/xcat/plugins/dhcp.pm
+++ b/xCAT-server/lib/xcat/plugins/dhcp.pm
@@ -395,7 +395,7 @@ sub addnode
         if ($nrent and $nrent->{netboot} and $nrent->{netboot} eq 'xnba' and $lstatements !~ /filename/) {
             if (-f "$tftpdir/xcat/xnba.kpxe") {
                 if ($doiscsi and $chainent and $chainent->{currstate} and ($chainent->{currstate} eq 'iscsiboot' or $chainent->{currstate} eq 'boot')) {
-                    $lstatements = 'if option client-architecture = 00:00 and not gpxe.bus-id { filename = \"xcat/xnba.kpxe\"; } else { filename = \"\"; } '.$lstatements;
+                    $lstatements = 'if option client-architecture = 00:00 and not exists gpxe.bus-id { filename = \"xcat/xnba.kpxe\"; } else { filename = \"\"; } '.$lstatements;
                 } else {
 			#TODO: if windows uefi, do vendor-class-identifier of "PXEClient" to bump it over to proxydhcp.c
 		    if (($douefi == 2 and $chainent->{currstate} =~ /^install/) or $chainent->{currstate} =~ /^winshell/) { #proxy dhcp required in uefi invocation