diff --git a/ChangeLog b/ChangeLog
index a08d6b3ba1..faf3fe9c02 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Nov  5 21:21:47 2013  Tanaka Akira  <akr@fsij.org>
+
+	* test/ruby/test_thread.rb (test_thread_join_in_trap):
+	  Run the test in a different process.
+
 Tue Nov  5 20:14:32 2013  Masaya Tarui  <tarui@ruby-lang.org>
 
 	* gc.c (is_live_object): A hidden object may be a live object.
diff --git a/test/ruby/test_thread.rb b/test/ruby/test_thread.rb
index 260c654287..ab1b81a8fe 100644
--- a/test/ruby/test_thread.rb
+++ b/test/ruby/test_thread.rb
@@ -725,6 +725,7 @@ _eom
   end
 
   def test_thread_join_in_trap
+    assert_separately [], <<-'EOS'
     assert_nothing_raised{
       t = Thread.new{ sleep 0.2; Process.kill(:INT, $$) }
 
@@ -734,7 +735,9 @@ _eom
 
       t.join
     }
+    EOS
 
+    assert_separately [], <<-'EOS'
     assert_equal(:normal_end,
                  begin
                    t = Thread.new{ sleep 0.2; Process.kill(:INT, $$); :normal_end }
@@ -745,6 +748,7 @@ _eom
                    t.value
                  end
                  )
+    EOS
   end
 
   def test_thread_join_current