diff --git a/chinese/bitchx/files/patch-include::config.h b/chinese/bitchx/files/patch-include::config.h
index dc6276edec65..ccd29ebd4759 100644
--- a/chinese/bitchx/files/patch-include::config.h
+++ b/chinese/bitchx/files/patch-include::config.h
@@ -25,8 +25,8 @@
 +#ifdef WANT_BIG5
 +/* XXX I didn't check the encoding range of big5+. This is standard big5. */
 +#define is_big5_los(lo) (((char)0x40<=lo)&&(lo<=(char)0x7E))        /* standard */
-+#define is_big5_lox(lo) (((char)0xA1<=lo)&&(lo<=(char)0xFE))        /* extended */
-+#define is_big5_hi(hi)  (((char)0xA1<=hi)&&(hi<=(char)0xFE))
++#define is_big5_lox(lo) (((char)0x80<=lo)&&(lo<=(char)0xFE))        /* extended */
++#define is_big5_hi(hi)  (((char)0x81<=hi)&&(hi<=(char)0xFE))
 +#define is_big5(hi,lo) is_big5_hi(hi) && (is_big5_los(lo) || is_big5_lox(lo))
 +#endif WANT_BIG5
 +