diff --git a/ChangeLog b/ChangeLog
index a214a8ed07..eaf4bb2913 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sat Sep  6 18:38:47 2008  Tanaka Akira  <akr@fsij.org>
+
+	* transcode.c (allocate_converted_string): fix overflow condition.
+
 Sat Sep  6 15:06:21 2008  Tanaka Akira  <akr@fsij.org>
 
 	* transcode.c (sym_html): new variable.
diff --git a/transcode.c b/transcode.c
index cc3fc53c7a..ccb54dfff0 100644
--- a/transcode.c
+++ b/transcode.c
@@ -1445,7 +1445,7 @@ allocate_converted_string(const char *sname, const char *dname,
     res = rb_econv_convert(ec, &sp, str+len, &dp, dst_str+dst_bufsize, 0);
     dst_len = dp - dst_str;
     while (res == econv_destination_buffer_full) {
-        if (dst_bufsize * 2 < dst_bufsize) {
+        if (SIZE_MAX/2 < dst_bufsize) {
             goto fail;
         }
         dst_bufsize *= 2;