Fuzzy match function in C

fuzzy.c

#include <ctype.h>

int fuzzy_match(const char *needle, const char *haystack)
{
    while (*needle && *haystack) {
        if (*haystack == tolower(*needle) || *haystack == toupper(*needle)) {
            needle++;
        }

        haystack++;
    }

    return !*needle;
}