diff --git a/lighthub/monitor.bat b/lighthub/monitor.bat
new file mode 100644
index 0000000..895fb94
--- /dev/null
+++ b/lighthub/monitor.bat
@@ -0,0 +1 @@
+pio device monitor -b 115200
diff --git a/lighthub/utils.cpp b/lighthub/utils.cpp
index 55f5f5e..0a63f56 100644
--- a/lighthub/utils.cpp
+++ b/lighthub/utils.cpp
@@ -377,7 +377,7 @@ void printIPAddress(IPAddress ipAddress) {
 }
 
 
-char* setTopic(char* buf, int8_t buflen, topicType tt, char* suffix)
+char* setTopic(char* buf, int8_t buflen, topicType tt, const char* suffix)
 {
   aJsonObject *_root = NULL;
   aJsonObject *_l2 = NULL;
diff --git a/lighthub/utils.h b/lighthub/utils.h
index 83171ef..712fd2a 100644
--- a/lighthub/utils.h
+++ b/lighthub/utils.h
@@ -55,7 +55,7 @@ void ReadUniqueID( uint32_t * pdwUniqueID );
 int inet_aton(const char* aIPAddrString, IPAddress& aResult);
 char *inet_ntoa_r(IPAddress addr, char *buf, int buflen);
 void printIPAddress(IPAddress ipAddress);
-char* setTopic(char* buf, int8_t buflen, topicType tt, char* suffix = NULL);
+char* setTopic(char* buf, int8_t buflen, topicType tt, const char* suffix = NULL);
 void printUlongValueToStr(char *valstr, unsigned long value);
 void scan_i2c_bus();
 void softRebootFunc();