   if(announce) {
     aJson.addStringToObject(announce, "devicename", "TI-CC3200");
     aJson.addStringToObject(announce, "uuid", uuid);
-    aJson.addStringToObject(announce, "mac", mac_string.c_str());
+    aJson.addStringToObject(announce, "mac", mac_string);
     aJson.addStringToObject(announce, "manufacturer", "Texas Instrument");
     aJson.addStringToObject(announce, "author", "cossb");
     aJson.addStringToObject(announce, "component", "cc3200button");

  }
  
  WiFi.macAddress(mac);
  for(int i=0;i<sizeof(mac);i++) {
    mac_string += String(mac[sizeof(mac)-1-i],HEX);
    if(i<(sizeof(mac)-1))
      mac_string += ":";
  }
  
  printWifiStatus();


  if(frame) {
    aJson.addStringToObject(frame, "devicename", "TI-CC3200");
    aJson.addStringToObject(frame, "uuid", uuid);
    aJson.addStringToObject(frame, "mac", mac_string);
    aJson.addStringToObject(frame, "component", "cc3200button");
    aJson.addStringToObject(frame, "command","buttonread");
    aJson.addBooleanToObject(frame, "button1", false);
