diff --git a/packages/node_modules/@node-red/nodes/core/network/10-mqtt.html b/packages/node_modules/@node-red/nodes/core/network/10-mqtt.html
index f665b738d..10acf4857 100644
--- a/packages/node_modules/@node-red/nodes/core/network/10-mqtt.html
+++ b/packages/node_modules/@node-red/nodes/core/network/10-mqtt.html
@@ -457,11 +457,11 @@
      * @param {string} topic
      * @returns `true` if it is a valid topic
      */
-    function validateMQTTPublishTopic(topic) {
-        if(!topic || topic == "") {
+    function validateMQTTPublishTopic(topic, opts) {
+        if(!topic || topic == "" || !/[\+#\b\f\n\r\t\v\0]/.test(topic)) {
             return true;
         }
-        return !/[\+#\b\f\n\r\t\v\0]/.test(topic);
+        return RED._("node-red:mqtt.errors.invalid-topic");
     }
     RED.nodes.registerType('mqtt-broker',{
         category: 'config',