diff --git a/networkDevices/W5500Device.cpp b/networkDevices/W5500Device.cpp
index ef0a531..0e0d8de 100644
--- a/networkDevices/W5500Device.cpp
+++ b/networkDevices/W5500Device.cpp
@@ -57,11 +57,10 @@ void W5500Device::initialize()
 
     if(_preferences->getBool(preference_mqtt_log_enabled))
     {
-        _path = new char[200];
-        memset(_path, 0, sizeof(_path));
-
         String pathStr = _preferences->getString(preference_mqtt_lock_path);
         pathStr.concat(mqtt_topic_log);
+        _path = new char[pathStr.length() + 1];
+        memset(_path, 0, sizeof(_path));
         strcpy(_path, pathStr.c_str());
         Log = new MqttLogger(this, _path, MqttLoggerMode::MqttAndSerial);
     }