diff --git a/ChangeLog b/ChangeLog
index 2a1987feed..a07d1ab47c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Apr 24 22:38:55 2014  Tanaka Akira  <akr@fsij.org>
+
+	* bootstraptest/test_io.rb: Don't use tmpdir because etc.so is not
+	  usable from miniruby.
+
 Thu Apr 24 21:09:55 2014  Kazuhiro NISHIYAMA  <zn@mbf.nifty.com>
 
 	* man/ruby.1: fix broken link.
diff --git a/bootstraptest/test_io.rb b/bootstraptest/test_io.rb
index f7360f34b3..c37888fb1a 100644
--- a/bootstraptest/test_io.rb
+++ b/bootstraptest/test_io.rb
@@ -42,9 +42,8 @@ assert_finish 1, %q{
 }
 
 assert_equal 'ok', %q{
-  require 'tmpdir'
   begin
-    tmpname = "#{Dir.tmpdir}/ruby-btest-#{$$}-#{rand(0x100000000).to_s(36)}"
+    tmpname = "/tmp/ruby-btest-#{$$}-#{rand(0x100000000).to_s(36)}"
     rw = File.open(tmpname, File::RDWR|File::CREAT|File::EXCL)
   rescue Errno::EEXIST
     retry
@@ -58,9 +57,8 @@ assert_equal 'ok', %q{
 }
 
 assert_equal 'ok', %q{
-  require 'tmpdir'
   begin
-    tmpname = "#{Dir.tmpdir}/ruby-btest-#{$$}-#{rand(0x100000000).to_s(36)}"
+    tmpname = "/tmp/ruby-btest-#{$$}-#{rand(0x100000000).to_s(36)}"
     rw = File.open(tmpname, File::RDWR|File::CREAT|File::EXCL)
   rescue Errno::EEXIST
     retry