diff --git a/packages/node_modules/@node-red/nodes/core/network/10-mqtt.js b/packages/node_modules/@node-red/nodes/core/network/10-mqtt.js
index db6cfba73..afa0066f4 100644
--- a/packages/node_modules/@node-red/nodes/core/network/10-mqtt.js
+++ b/packages/node_modules/@node-red/nodes/core/network/10-mqtt.js
@@ -158,9 +158,16 @@ module.exports = function(RED) {
             if(!keys || !keys.length) return null;
             keys.forEach(key => {
                 let val = srcUserProperties[key];
-                if(typeof val == "string") {
+                if(typeof val === "string") {
                     count++;
                     _clone[key] = val;
+                } else if (val !== undefined && val !== null) {
+                    try {
+                        _clone[key] = JSON.stringify(val)
+                        count++;
+                    } catch  (err) {
+                        // Silently drop property
+                    }
                 }
             });
             if(count) properties.userProperties = _clone;