diff --git a/ChangeLog b/ChangeLog
index da543b86e1..f9215d0af8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sat Dec 25 15:08:08 2010  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* ext/pty/pty.c (chfunc): Added rb_thread_atfork_before_exec().
+	  We must reinitialize GVL at new process creation. Otherwise
+	  we may meet an insane deadlock. [Bug#4121][ruby-dev:42686]
+
 Wed Sep  8 22:46:31 2010  NAKAMURA, Hiroshi  <nahi@ruby-lang.org>
 
 	* ext/openssl/ossl_ssl.c (ssl_get_error): Thread context switch was
diff --git a/ext/pty/pty.c b/ext/pty/pty.c
index 1d7aac6817..800e75959b 100644
--- a/ext/pty/pty.c
+++ b/ext/pty/pty.c
@@ -166,6 +166,8 @@ chfunc(void *data)
     struct exec_info arg;
     int status;
 
+    rb_thread_atfork_before_exec();
+
     /*
      * Set free from process group and controlling terminal
      */
diff --git a/version.h b/version.h
index 3532fc99cb..c4c16fc29a 100644
--- a/version.h
+++ b/version.h
@@ -1,5 +1,5 @@
 #define RUBY_VERSION "1.9.2"
-#define RUBY_PATCHLEVEL 135
+#define RUBY_PATCHLEVEL 136
 #define RUBY_VERSION_MAJOR 1
 #define RUBY_VERSION_MINOR 9
 #define RUBY_VERSION_TEENY 1