diff --git a/ChangeLog b/ChangeLog
index 1ff2f28acd..d09277caac 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sat Dec 15 21:38:24 2007  Tanaka Akira  <akr@fsij.org>
+
+	* lib/timeout.rb: join the background thread to make sure it is dead.
+
 Sat Dec 15 20:20:48 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* configure.in (enc/Makefile): add external encoding objects list.
diff --git a/lib/timeout.rb b/lib/timeout.rb
index 19045d9491..d68312cf6d 100644
--- a/lib/timeout.rb
+++ b/lib/timeout.rb
@@ -45,7 +45,10 @@ module Timeout
       }
       return yield(sec)
     ensure
-      y.kill if y and y.alive?
+      if y and y.alive?
+        y.kill 
+        y.join # make sure y is dead.
+      end
     end
   end