diff --git a/src/opnsense/mvc/app/library/OPNsense/Firewall/Util.php b/src/opnsense/mvc/app/library/OPNsense/Firewall/Util.php
index db8726c69..0dc218190 100644
--- a/src/opnsense/mvc/app/library/OPNsense/Firewall/Util.php
+++ b/src/opnsense/mvc/app/library/OPNsense/Firewall/Util.php
@@ -195,8 +195,9 @@ class Util
         $tmp = explode(':', $number);
         foreach ($tmp as $port) {
             if (!getservbyname($port, "tcp") && !getservbyname($port, "udp")
-                && filter_var($port, FILTER_VALIDATE_INT, array(
-                    "options" => array("min_range"=>1, "max_range"=>65535))) === false
+                && (filter_var($port, FILTER_VALIDATE_INT, array(
+                    "options" => array("min_range"=>1, "max_range"=>65535))
+                  ) === false || !is_numeric($port))
             ) {
                 return false;
             }