ESP NOW mac address

I am trying to use ESP NOW to get two NodeMCU ESP32-s devices to communicate.
With the sample code below, it complies using the “0xFF” mac address, however when I change the mac it won’t compile and gives the error quoted below.

My assumption is that uint8_t is not define in the library, but the library does contain an esp_now.h file.
I’m using the Arduino IDE.

  Rui Santos
  Complete project details at
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files.
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.

#include <esp_now.h>
#include <WiFi.h>

uint8_t broadcastAddress[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
sketch_oct04a:5:31: error: unable to find numeric literal operator
'operator""C' uint8_t broadcastAddress[] = {8C, AA, B5, A2, 8E, 70};
Multiple libraries were found for "WiFi.h" Used:.. C:\Users######\AppData\Local\Arduino15\packages\esp32\hardware\esp32\1.0.4\libraries\WiFi
Not used: C:\Program Files (x86)\Arduino\libraries\WiFi exit status 1
exponent has no digits