diff --git a/ChangeLog b/ChangeLog
index 57560bbd7e..dba2821d37 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Jun  2 04:35:32 2008  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* enc/gb18030.c (gb18030_code_to_mbc): add 0x80000000
+	  for 4bytes character.
+
 Mon Jun  2 03:52:04 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ruby.c (set_arg0): reverted used variable definition.
diff --git a/enc/gb18030.c b/enc/gb18030.c
index f62a2394c9..d58abf8792 100644
--- a/enc/gb18030.c
+++ b/enc/gb18030.c
@@ -185,6 +185,9 @@ gb18030_mbc_to_code(const UChar* p, const UChar* end, OnigEncoding enc)
 static int
 gb18030_code_to_mbc(OnigCodePoint code, UChar *buf, OnigEncoding enc)
 {
+  if ((code & 0xff000000) != 0) {
+	code |= 0x80000000;
+  }
   return onigenc_mb4_code_to_mbc(enc, code, buf);
 }