fatal error: pgmspace.h: No such file or directory

I’m using FastCRC as a library in Arduino to calculate CRC. It works great on my Teensy 3.6, and I think this library has a hardware and software “version” and that the Teensy can utilize the hardware calculations with its built in crc hardware. The problem I’m having is that I’m trying to use this FastCRC library on my nRF52840, but I get the following error:

In file included from C:\Users\Mariu\Documents\Arduino\libraries\FastCRC2\FastCRCsw.cpp:38:0:
C:\Users\Mariu\Documents\Arduino\libraries\FastCRC2\FastCRC_tables.h:38:23: fatal error: pgmspace.h: No such file or directory
compilation terminated.
exit status 1
Error compiling for board SparkFun Pro nRF52840 Mini.

Now I’m aware of adding

#if defined(__AVR__ )
#include <avr/pgmspace.h>
#else
#include <pgmspace.h>	
#endif

This has already been done in the library for FastCRC. The library works great for my Teensy so I have no idea why it wouldn’t on the nRF52840. Any helpful suggestions would be appreciated!

so I have no idea why it wouldn't on the nRF52840.

In the core for this non-Arduino, do you HAVE a pgmspace.h file anywhere?