diff --git a/ChangeLog b/ChangeLog
index 486ec517f5..226a69edef 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Apr 27 06:20:13 2010  Tanaka Akira  <akr@fsij.org>
+
+	* io.c (select_internal): IO which cbuf is not empty is readable.
+
 Tue Apr 27 00:07:32 2010  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* parse.y (program): check void_expr when rb_parse_in_main().
diff --git a/io.c b/io.c
index 30150fc507..b1ca613169 100644
--- a/io.c
+++ b/io.c
@@ -7153,7 +7153,7 @@ select_internal(VALUE read, VALUE write, VALUE except, struct timeval *tp, rb_fd
 	for (i=0; i<RARRAY_LEN(read); i++) {
 	    GetOpenFile(rb_io_get_io(RARRAY_PTR(read)[i]), fptr);
 	    rb_fd_set(fptr->fd, &fds[0]);
-	    if (READ_DATA_PENDING(fptr)) { /* check for buffered data */
+	    if (READ_DATA_PENDING(fptr) || READ_CHAR_PENDING(fptr)) { /* check for buffered data */
 		pending++;
 		rb_fd_set(fptr->fd, &fds[3]);
 	    }
diff --git a/test/ruby/test_io_m17n.rb b/test/ruby/test_io_m17n.rb
index 98a52939d0..218a60b044 100644
--- a/test/ruby/test_io_m17n.rb
+++ b/test/ruby/test_io_m17n.rb
@@ -1774,5 +1774,15 @@ EOT
     }
   end
 
+
+  def test_cbuf_select
+    with_tmpdir {
+      r, w = IO.pipe
+      w << "\r\n"
+      r.set_encoding("US-ASCII:UTF-8", :universal_newline => true)
+      r.ungetc(r.getc)
+      assert_equal([[r],[],[]], IO.select([r], nil, nil, 1))
+    }
+  end
 end