diff --git a/ChangeLog b/ChangeLog
index 2cf512df72..c1c4c7e8ce 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,8 @@ Thu Jan 29 23:11:57 2004  WATANABE Hirofumi  <eban@ruby-lang.org>
 	* bcc32/Makefile.sub, win32/Makefile.sub, wince/Makefile.sub (DLEXT2):
 	  ditto.
 
+	* util.c (mblen): fix overrun.  [ruby-dev:22672]
+
 Thu Jan 29 22:41:53 2004  Dave Thomas  <dave@pragprog.com>
 
 	* lib/rdoc/generators/html_generator.rb: Allow 'link:' in Tidylinks.
diff --git a/util.c b/util.c
index a1e2dd34a7..13c4f87d09 100644
--- a/util.c
+++ b/util.c
@@ -296,6 +296,8 @@ mblen(const char *s, size_t n)
     if (s) {
 	if (n == 0 || *s == 0)
 	    return 0;
+	else if (!s[1])
+	    return 1;
 	return dbcs_table[(unsigned char)*s] + 1;
     }
     else