>>858
目視しかしてないけどこれっぽい？
jisx0208-MS.h:
 static int
 jisx0208_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
 {
     if (n >= 2)
     {
-unsigned char buf[2] = { s[0] & 0x80, s[1] & 0x80 };
+unsigned char buf[2] = { s[0] | 0x80, s[1] | 0x80 };
 ucs4_t wc;
 int ret;