diff --git a/udplogger.cpp b/udplogger.cpp
index 369af22..5f087b1 100644
--- a/udplogger.cpp
+++ b/udplogger.cpp
@@ -16,15 +16,15 @@ void UDPLogger::setName(String name){
     _name = name;
 }
 
-void UDPLogger::logString(String logmessage){
-    // wait 5 milliseconds if last send was less than 5 milliseconds before 
+void UDPLogger::logString(const String& logmessage){
+    // wait 5 milliseconds if last send was less than 5 milliseconds before
     if(millis() < (_lastSend + 5)){
         delay(5);
     }
-    logmessage = _name + ": " + logmessage;
-    Serial.println(logmessage);
+    // use fixed buffer instead of string concatenation to avoid heap fragmentation
+    snprintf(_packetBuffer, sizeof(_packetBuffer), "%s: %s", _name.c_str(), logmessage.c_str());
+    Serial.println(_packetBuffer);
     _Udp.beginPacketMulticast(_multicastAddr, _port, _interfaceAddr);
-    logmessage.toCharArray(_packetBuffer, 100);
     _Udp.print(_packetBuffer);
     _Udp.endPacket();
     _lastSend=millis();
diff --git a/udplogger.h b/udplogger.h
index c26fa49..e4cac28 100644
--- a/udplogger.h
+++ b/udplogger.h
@@ -22,7 +22,7 @@ class UDPLogger{
         UDPLogger();
         UDPLogger(IPAddress interfaceAddr, IPAddress multicastAddr, int port);
         void setName(String name);
-        void logString(String logmessage);
+        void logString(const String& logmessage);
         void logColor24bit(uint32_t color);
     private:
         String _name;