diff --git a/ChangeLog b/ChangeLog
index 9a317b8d6f..b35d25bae5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Sep 23 21:45:02 2008  Tanaka Akira  <akr@fsij.org>
+
+	* io.c (copy_stream_body): use io_binwrite instead of io_fwrite.
+
 Tue Sep 23 21:31:16 2008  Tadayoshi Funaba  <tadf@dotrb.org>
 
 	* test/ruby/test_rational2.rb: updated.
diff --git a/io.c b/io.c
index 12eb6aa97f..cc59b1bbdc 100644
--- a/io.c
+++ b/io.c
@@ -7464,7 +7464,7 @@ copy_stream_body(VALUE arg)
         rb_str_resize(str,len);
         read_buffered_data(RSTRING_PTR(str), len, src_fptr);
         if (dst_fptr) /* IO or filename */
-            io_fwrite(str, dst_fptr, 0);
+            io_binwrite(str, dst_fptr, 0);
         else /* others such as StringIO */
             rb_io_write(stp->dst, str);
         stp->total += len;