warning: assignment discards qualifiers from pointer target type

I wrote the following code:

void buildArrays(char *pLastLetter[],int length[], int size, const char str[]) {

    int i;
    int strIndex = 0;
    int letterCounter = 0;

    for (i=0; i<size; i++) {

        while ( (str[strIndex] != SEPERATOR) || (str[strIndex] != '\0') ) {
            letterCounter++;
            strIndex++;
        }
        pLastLetter[i] = &str[strIndex-1];
        length[i] = letterCounter;
        letterCounter = 0;
        strIndex++;
    }
}

and I'm getting the above warning on pLastLetter[i] = &str[strIndex-1];

pLastLetter is a pointers array that points to a char in str[].

Anyone knows why I'm getting it and how to fix it?