How do I fix this error? 

Invalid read of size 4
==13752==    at 0x4900657: fgets (iofgets.c:47)
==13752==    by 0x1094B2: parse_file (parse.c:17)
==13752==    by 0x10984B: main (parse.c:197)
==13752==  Address 0x0 is not stack'd, malloc'd or (recently) free'd

This is line 17:  while(fgets(line, MAXLINE, fp) != NULL){