openssl RAND_load_file always returns 0

I'm trying to read from /dev/random/ on linux using.

int bytes = RAND_load_file("/dev/random", 16); printf("%d bytes read", bytes);

This always outputs 0 bytes read.

/dev/random is being fed by a software entropy source. I made sure /dev/random does have enough data. According to docs RAND_load_file should return no. of bytes read but this is not happening.