diff --git a/perl-xCAT/xCAT/NetworkUtils.pm b/perl-xCAT/xCAT/NetworkUtils.pm
index b5fb6c9f4..f8ba36b9e 100755
--- a/perl-xCAT/xCAT/NetworkUtils.pm
+++ b/perl-xCAT/xCAT/NetworkUtils.pm
@@ -377,7 +377,7 @@ sub ishostinsubnet {
     $ip = getipaddr($ip,GetNumber=>1);
     $subnet = getipaddr($subnet,GetNumber=>1);
     $ip &= $mask;
-    if ($ip == $subnet) {
+    if ($ip && $subnet && ($ip == $subnet)) {
         return 1;
     } else {
         return 0;