diff --git a/ChangeLog b/ChangeLog
index 9543675070..dc675a9357 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Jul 22 01:20:54 2009  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* bootstraptest/test_io.rb: block write may block for long time.
+
 Wed Jul 22 00:34:39 2009  Keiju Ishitsuka  <keiju@ruby-lang.org>
 
 	* lib/irb.rb, lib/irb/init.rb, lib/irb/ext/save-history.rb: add
@@ -14,7 +18,6 @@ Tue Jul 21 21:37:19 2009  Keiju Ishitsuka  <keiju@ruby-lang.org>
 
 	* lib/irb/cmd/help.rb: fixed irb's "help" command. [ruby-core:22310].
 
-Tue Jul 21 20:41:20 2009  Keiju Ishitsuka  <keiju@ruby-lang.org>
 
 	* lib/tracer.rb: no show lines unkonwn line number. [ruby-core:22096],
           no trace display  c-call and c-return as default.
diff --git a/bootstraptest/test_io.rb b/bootstraptest/test_io.rb
index 83b38f8cce..2294654211 100644
--- a/bootstraptest/test_io.rb
+++ b/bootstraptest/test_io.rb
@@ -11,19 +11,22 @@ assert_finish 5, %q{
 assert_finish 10, %q{
   begin
     require "io/nonblock"
-    r, w = IO.pipe
-    w.nonblock = true
-    w.write_nonblock("a" * 100000)
-    w.nonblock = false
-    t1 = Thread.new { w.write("b" * 4096) }
-    t2 = Thread.new { w.write("c" * 4096) }
-    sleep 0.5
-    r.sysread(4096).length
-    sleep 0.5
-    r.sysread(4096).length
-    t1.join
-    t2.join
-  rescue LoadError
+    require "timeout"
+    timeout(3) do
+      r, w = IO.pipe
+      w.nonblock = true
+      w.write_nonblock("a" * 100000)
+      w.nonblock = false
+      t1 = Thread.new { w.write("b" * 4096) }
+      t2 = Thread.new { w.write("c" * 4096) }
+      sleep 0.5
+      r.sysread(4096).length
+      sleep 0.5
+      r.sysread(4096).length
+      t1.join
+      t2.join
+    end
+  rescue LoadError, TimeoutError
   end
 }, '[ruby-dev:32566]'