missing hwlib.h: No such file or directory

The complete error message is as follows

$ make

arm-linux-gnueabihf-gcc -g -Wall -Werror -std=c99 -Dsoc_cv_av -I/cygdrive/c/intelFPGA/18.1/embedded/ip/altera/hps/altera_hps/hwlib/include -I/cygdrive/c/intelFPGA/18.1/embedded/ip/altera/hps/altera_hps/hwlib/include/soc_cv_av -I/cygdrive/c/intelFPGA/18.1/embedded/ip/altera/hps/altera_hps/hwlib/include/soc_cv_av/ -c main.c -o main.o

main.c:63:19: fatal error: hwlib.h: No such file or directory

#include "hwlib.h"

^

compilation terminated.

make: *** [main.o] Error 1

From other forums I found out that including "cygdrive/c/intelFPGA/18.1/embedded/ip/altera/hps/altera_hps/hwlib/include" and "cygdrive/c/intelFPGA/18.1/embedded/ip/altera/hps/altera_hps/hwlib/include/soc_cv_av" should ideally solve the problem. But for some reason I still seem to be getting this error. If I go to this directory and list (ls) the files I can find hwlib.h but somehow the system is unable to do this.

Please help