diff --git a/ChangeLog b/ChangeLog
index 611199bc97..c68b0838b4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Tue Jul 23 19:44:32 2013  Koichi Sasada  <ko1@atdot.net>
+
+	* thread_native.h: add rb_nativethread_self() which returns
+	  current running native thread identifier.
+
+	* thread_[pthread|win32].c: implement rb_nativethread_self().
+
 Tue Jul 23 19:34:11 2013  Koichi Sasada  <ko1@atdot.net>
 
 	* thread_pthread.h, thread_win32.h: rename rb_thread_id_t to
diff --git a/thread_native.h b/thread_native.h
index 2870b895c6..aa037d205f 100644
--- a/thread_native.h
+++ b/thread_native.h
@@ -11,6 +11,8 @@
 
 RUBY_SYMBOL_EXPORT_BEGIN
 
+rb_nativethread_id_t rb_nativethread_self();
+
 void rb_nativethread_lock_initialize(rb_nativethread_lock_t *lock);
 void rb_nativethread_lock_destroy(rb_nativethread_lock_t *lock);
 void rb_nativethread_lock_lock(rb_nativethread_lock_t *lock);
diff --git a/thread_pthread.c b/thread_pthread.c
index e13e26786e..1b4ec10b98 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -1535,4 +1535,10 @@ rb_reserved_fd_p(int fd)
 #endif
 }
 
+rb_nativethread_id_t
+rb_nativethread_self(void)
+{
+    return pthread_self();
+}
+
 #endif /* THREAD_SYSTEM_DEPENDENT_IMPLEMENTATION */
diff --git a/thread_win32.c b/thread_win32.c
index b484fece8e..250b2b7b80 100644
--- a/thread_win32.c
+++ b/thread_win32.c
@@ -766,4 +766,11 @@ rb_reserved_fd_p(int fd)
 {
     return 0;
 }
+
+rb_nativethread_id_t
+rb_nativethread_self(void)
+{
+    return GetCurrentThread();
+}
+
 #endif /* THREAD_SYSTEM_DEPENDENT_IMPLEMENTATION */