diff --git a/etc/inc/captiveportal.inc b/etc/inc/captiveportal.inc
index dbed5977d9..4f990f8b24 100644
--- a/etc/inc/captiveportal.inc
+++ b/etc/inc/captiveportal.inc
@@ -322,8 +322,10 @@ EOD;
 			mwexec("/sbin/kldunload ipfw.ko");
 		$listifs = get_configured_interface_list_by_realif();
 		foreach ($listifs as $listrealif => $listif) {
-			mwexec("/sbin/ifconfig {$listrealif} -ipfwfilter");
-			$carpif = link_ip_to_carp_interface(find_interface_ip($listrealif));
+			if (!empty($listrealif)) {
+				mwexec("/sbin/ifconfig {$listrealif} -ipfwfilter");
+				$carpif = link_ip_to_carp_interface(find_interface_ip($listrealif));
+			}
                         if (!empty($carpif)) {
 				$carpsif = explode(" ", $carpif);
 				foreach ($carpsif as $cpcarp)
diff --git a/etc/inc/util.inc b/etc/inc/util.inc
index 0915f033f9..156e4f4f51 100644
--- a/etc/inc/util.inc
+++ b/etc/inc/util.inc
@@ -1112,4 +1112,4 @@ function is_URL($url) {
 	return false;
 }
 
-?>
\ No newline at end of file
+?>