diff --git a/ChangeLog b/ChangeLog
index b17b133f7c..bb7a132b20 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Jul 12 14:07:46 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* signal.c (install_sighandler): fixed a race.
+
 Tue Jul 12 13:49:32 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* signal.c (sig_trap): don't permit to change a signal handler which
diff --git a/signal.c b/signal.c
index 7490de9f82..d98aa03b53 100644
--- a/signal.c
+++ b/signal.c
@@ -1008,10 +1008,12 @@ install_sighandler(int signum, sighandler_t handler)
 {
     sighandler_t old;
 
+    rb_disable_interrupt();
     old = ruby_signal(signum, handler);
     if (old != SIG_DFL) {
 	ruby_signal(signum, old);
     }
+    rb_enable_interrupt();
 }
 
 #if defined(SIGCLD) || defined(SIGCHLD)