C :: Warning - Return Makes Pointer From Integer Without A Cast

I have a function that I want to exit gracefully when an "error" occurs in an input file. My function declaration is:

Code: BSTnode *buildTree(FILE *fp)

The few lines that are causing the problems are:

Code: if(regcomp(®ex, to_find, REG_EXTENDED | REG_NEWLINE) != 0) {
fprintf(stderr, "Failed to compile regex '%s'
", to_find);
return EXIT_FAILURE;
}

I know that if I just use "return" by itself the warning goes away but fails to exit when the error occurs. I also believe this may not be the correct use of stderr. But I need the program to exit when an error has occurred.