diff --git a/wled00/cfg.cpp b/wled00/cfg.cpp
index cafba6a0ab..4234d9b016 100644
--- a/wled00/cfg.cpp
+++ b/wled00/cfg.cpp
@@ -442,14 +442,14 @@ bool deserializeConfig(JsonObject doc, bool fromFS) {
 #ifdef WLED_ENABLE_MQTT
   JsonObject if_mqtt = interfaces["mqtt"];
   CJSON(mqttEnabled, if_mqtt["en"]);
-  getStringFromJson(mqttServer, if_mqtt[F("broker")], 33);
+  getStringFromJson(mqttServer, if_mqtt[F("broker")], MQTT_MAX_SERVER_LEN+1);
   CJSON(mqttPort, if_mqtt["port"]); // 1883
   getStringFromJson(mqttUser, if_mqtt[F("user")], 41);
   getStringFromJson(mqttPass, if_mqtt["psk"], 65); //normally not present due to security
   getStringFromJson(mqttClientID, if_mqtt[F("cid")], 41);
 
-  getStringFromJson(mqttDeviceTopic, if_mqtt[F("topics")][F("device")], 33); // "wled/test"
-  getStringFromJson(mqttGroupTopic, if_mqtt[F("topics")][F("group")], 33); // ""
+  getStringFromJson(mqttDeviceTopic, if_mqtt[F("topics")][F("device")], MQTT_MAX_TOPIC_LEN+1); // "wled/test"
+  getStringFromJson(mqttGroupTopic, if_mqtt[F("topics")][F("group")], MQTT_MAX_TOPIC_LEN+1); // ""
   CJSON(retainMqttMsg, if_mqtt[F("rtn")]);
 #endif
 
diff --git a/wled00/set.cpp b/wled00/set.cpp
index 71db6c0675..48cdfbf6b2 100644
--- a/wled00/set.cpp
+++ b/wled00/set.cpp
@@ -347,14 +347,14 @@ void handleSettingsSet(AsyncWebServerRequest *request, byte subPage)
 
     #ifdef WLED_ENABLE_MQTT
     mqttEnabled = request->hasArg(F("MQ"));
-    strlcpy(mqttServer, request->arg(F("MS")).c_str(), 33);
+    strlcpy(mqttServer, request->arg(F("MS")).c_str(), MQTT_MAX_SERVER_LEN+1);
     t = request->arg(F("MQPORT")).toInt();
     if (t > 0) mqttPort = t;
     strlcpy(mqttUser, request->arg(F("MQUSER")).c_str(), 41);
     if (!isAsterisksOnly(request->arg(F("MQPASS")).c_str(), 41)) strlcpy(mqttPass, request->arg(F("MQPASS")).c_str(), 65);
     strlcpy(mqttClientID, request->arg(F("MQCID")).c_str(), 41);
-    strlcpy(mqttDeviceTopic, request->arg(F("MD")).c_str(), 33);
-    strlcpy(mqttGroupTopic, request->arg(F("MG")).c_str(), 33);
+    strlcpy(mqttDeviceTopic, request->arg(F("MD")).c_str(), MQTT_MAX_TOPIC_LEN+1);
+    strlcpy(mqttGroupTopic, request->arg(F("MG")).c_str(), MQTT_MAX_TOPIC_LEN)+1;
     buttonPublishMqtt = request->hasArg(F("BM"));
     retainMqttMsg = request->hasArg(F("RT"));
     #endif
diff --git a/wled00/wled.h b/wled00/wled.h
index 0d22e23dee..3bfcc1001d 100644
--- a/wled00/wled.h
+++ b/wled00/wled.h
@@ -429,12 +429,18 @@ WLED_GLOBAL uint16_t pollReplyCount _INIT(0);                     // count numbe
 // mqtt
 WLED_GLOBAL unsigned long lastMqttReconnectAttempt _INIT(0);  // used for other periodic tasks too
 #ifndef WLED_DISABLE_MQTT
+  #ifndef MQTT_MAX_TOPIC_LEN
+    #define MQTT_MAX_TOPIC_LEN 32
+  #endif
+  #ifndef MQTT_MAX_SERVER_LEN
+    #define MQTT_MAX_SERVER_LEN 32
+  #endif
 WLED_GLOBAL AsyncMqttClient *mqtt _INIT(NULL);
 WLED_GLOBAL bool mqttEnabled _INIT(false);
 WLED_GLOBAL char mqttStatusTopic[40] _INIT("");            // this must be global because of async handlers
-WLED_GLOBAL char mqttDeviceTopic[33] _INIT("");            // main MQTT topic (individual per device, default is wled/mac)
-WLED_GLOBAL char mqttGroupTopic[33] _INIT("wled/all");     // second MQTT topic (for example to group devices)
-WLED_GLOBAL char mqttServer[33] _INIT("");                 // both domains and IPs should work (no SSL)
+WLED_GLOBAL char mqttDeviceTopic[MQTT_MAX_TOPIC_LEN+1] _INIT("");         // main MQTT topic (individual per device, default is wled/mac)
+WLED_GLOBAL char mqttGroupTopic[MQTT_MAX_TOPIC_LEN+1]  _INIT("wled/all"); // second MQTT topic (for example to group devices)
+WLED_GLOBAL char mqttServer[MQTT_MAX_SERVER_LEN+1]     _INIT("");         // both domains and IPs should work (no SSL)
 WLED_GLOBAL char mqttUser[41] _INIT("");                   // optional: username for MQTT auth
 WLED_GLOBAL char mqttPass[65] _INIT("");                   // optional: password for MQTT auth
 WLED_GLOBAL char mqttClientID[41] _INIT("");               // override the client ID
diff --git a/wled00/xml.cpp b/wled00/xml.cpp
index c2504cf92d..c2e4ced7aa 100644
--- a/wled00/xml.cpp
+++ b/wled00/xml.cpp
@@ -478,6 +478,7 @@ void getSettingsJS(byte subPage, char* dest)
 
   if (subPage == SUBPAGE_SYNC)
   {
+    char nS[32];
     sappend('v',SET_F("UP"),udpPort);
     sappend('v',SET_F("U2"),udpPort2);
     sappend('v',SET_F("GS"),syncGroups);
@@ -534,6 +535,9 @@ void getSettingsJS(byte subPage, char* dest)
     sappends('s',SET_F("MG"),mqttGroupTopic);
     sappend('c',SET_F("BM"),buttonPublishMqtt);
     sappend('c',SET_F("RT"),retainMqttMsg);
+    oappend(SET_F("d.Sf.MD.maxlength=")); oappend(itoa(MQTT_MAX_TOPIC_LEN,nS,10));  oappend(SET_F(";"));
+    oappend(SET_F("d.Sf.MG.maxlength=")); oappend(itoa(MQTT_MAX_TOPIC_LEN,nS,10));  oappend(SET_F(";"));
+    oappend(SET_F("d.Sf.MS.maxlength=")); oappend(itoa(MQTT_MAX_SERVER_LEN,nS,10));  oappend(SET_F(";"));
     #else
     oappend(SET_F("toggle('MQTT');"));    // hide MQTT settings
     #endif