fgetws segfaults after a few iterations

I'm trying to create a container that holds the Japanese alphabet, so I'm using the data type wchar_t, and have my .c and .txt files encoded in UTF-8. The idea is that the program populates the container by reading in the .txt file. I can read in the first few lines, but after a few iterations the program segfaults. I suspect it is fgetws because of a few wprintf statements that I've put around the function.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <locale.h>

typedef struct entry {
    wchar_t romaji[5];
} entry;

typedef struct dictionary {
    struct entry entry[46];
} dictionary;

void init_dictionary(dictionary **dictionary) {
    (*dictionary) = malloc(sizeof(dictionary));
}

void add_romaji(dictionary *dictionary, wchar_t *romaji, int index) {
    entry new;

    wcscpy(new.romaji, romaji);

    dictionary->entry[index] = new;
}

void populate(dictionary *dictionary) {
    FILE *fp;
    wchar_t line[5];
    wchar_t *ptr;
    wchar_t romaji[5];
    int i;

    fp = fopen("romaji.txt", "r");
    i = 0;

    while(fgetws(line, 5, fp) != NULL) {
        wcstok(line, L"\n", &ptr);
        wcscpy(romaji, line);
        add_romaji(dictionary, romaji, i);
        ++i;
    }

    fclose(fp);
}

int main(int argc, char ** argv) {
    setlocale(LC_CTYPE, "");

    dictionary *dictionary;

    init_dictionary(&dictionary);
    populate(dictionary);

    return EXIT_SUCCESS;
}

romaji.txt is in UTF-8, and just contains a line for each character in the Japanese alphabet. I'm unable to get the indentation here to work, so I cannot post it, sorry. I tried searching for an answer, but none have helped. If anyone could let me know what my mistake is, I would appreciate it.