diff --git a/ChangeLog b/ChangeLog
index f1dd660f01..9f3801b51e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Tue Dec 21 00:46:20 2010  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* thread.c (thread_cleanup_func): Don't touch native threading
+	  resource at fork. Sadly this is purely bandaid. We need to
+	  implement proper fix later. [Bug #4169] [ruby-core:33767]
+
 Tue Dec 21 00:22:44 2010  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* error.c (exit_success_p): Check status code more carefully.
diff --git a/thread.c b/thread.c
index ac032ef689..c46a5bc445 100644
--- a/thread.c
+++ b/thread.c
@@ -391,12 +391,21 @@ thread_cleanup_func_before_exec(void *th_ptr)
 }
 
 static void
-thread_cleanup_func(void *th_ptr)
+thread_cleanup_func(void *th_ptr, int atfork)
 {
     rb_thread_t *th = th_ptr;
 
     th->locking_mutex = Qfalse;
     thread_cleanup_func_before_exec(th_ptr);
+
+    /*
+     * Unfortunately, we can't release native threading resource at fork
+     * because libc may have unstable locking state therefore touching
+     * a threading resource may cause a deadlock.
+     */
+    if (atfork)
+	return;
+
     native_thread_destroy(th);
 }
 
@@ -525,7 +534,7 @@ thread_start_func_2(rb_thread_t *th, VALUE *stack_start, VALUE *register_stack_s
 	ruby_cleanup(state);
     }
     else {
-	thread_cleanup_func(th);
+	thread_cleanup_func(th, FALSE);
 	gvl_release(th->vm);
     }
 
@@ -2780,7 +2789,7 @@ terminate_atfork_i(st_data_t key, st_data_t val, st_data_t current_th)
 	    rb_mutex_abandon_all(th->keeping_mutexes);
 	}
 	th->keeping_mutexes = NULL;
-	thread_cleanup_func(th);
+	thread_cleanup_func(th, TRUE);
     }
     return ST_CONTINUE;
 }