diff --git a/qse/include/qse/si/App.hpp b/qse/include/qse/si/App.hpp
index c6ffc14d..2552d770 100644
--- a/qse/include/qse/si/App.hpp
+++ b/qse/include/qse/si/App.hpp
@@ -59,6 +59,7 @@ public:
 
 	void sleep (const qse_ntime_t* duration) QSE_CPP_NOEXCEPT;
 	void sleep (unsigned int seconds) QSE_CPP_NOEXCEPT;
+	void msleep (qse_mtime_t duration) QSE_CPP_NOEXCEPT;
 
 #if 0
 	int switchUser (qse_uid_t uid, qse_gid_t gid, bool permanently) QSE_CPP_NOEXCEPT;
diff --git a/qse/include/qse/si/Thread.hpp b/qse/include/qse/si/Thread.hpp
index ecb49f53..8ed39876 100644
--- a/qse/include/qse/si/Thread.hpp
+++ b/qse/include/qse/si/Thread.hpp
@@ -99,6 +99,11 @@ public:
 		static qse_ntime_t duration = { seconds, 0 };
 		qse_sleep (&duration);
 	}
+
+	void msleep (qse_mtime_t duration) QSE_CPP_NOEXCEPT
+	{
+		qse_msleep (duration);
+	}
 		
 protected:
 	qse_thr_t thr;
diff --git a/qse/include/qse/si/os.h b/qse/include/qse/si/os.h
index 91aefe7a..e0f734e3 100644
--- a/qse/include/qse/si/os.h
+++ b/qse/include/qse/si/os.h
@@ -42,6 +42,10 @@ QSE_EXPORT void qse_sleep (
 	const qse_ntime_t* interval
 );
 
+QSE_EXPORT void qse_msleep (
+	const qse_mtime_t interval
+);
+
 #if defined(__cplusplus)
 }
 #endif
diff --git a/qse/lib/si/App.cpp b/qse/lib/si/App.cpp
index 26d13d6b..cb60295b 100644
--- a/qse/lib/si/App.cpp
+++ b/qse/lib/si/App.cpp
@@ -207,6 +207,11 @@ void App::sleep (unsigned int seconds) QSE_CPP_NOEXCEPT
 	qse_sleep (&duration);
 }
 
+void App::msleep (const qse_mtime_t duration) QSE_CPP_NOEXCEPT
+{
+	qse_msleep (duration);
+}
+
 #if 0
 int App::switchPrivilege (int gid, int uid, bool permanently)
 {
diff --git a/qse/lib/si/os.c b/qse/lib/si/os.c
index 3568c7d1..54e04c2c 100644
--- a/qse/lib/si/os.c
+++ b/qse/lib/si/os.c
@@ -56,6 +56,23 @@ void qse_sleep (const qse_ntime_t* interval)
 #endif
 }
 
+void qse_msleep (qse_mtime_t interval)
+{
+#if defined(_WIN32)
+	Sleep (interval);
+#elif defined(__OS2__)
+	DosSleep (interval);
+#elif defined(HAVE_NANOSLEEP)
+	struct timespec ts;
+	ts.tv_sec = QSE_MSEC_TO_SEC(interval);
+	interval -= QSE_SEC_TO_MSEC(ts.tv_sec);
+	ts.tv_nsec = QSE_MSEC_TO_NSEC(interval);
+	nanosleep (&ts, &ts);
+#else
+	sleep (QSE_MSEC_TO_SEC(interval));
+#endif
+}
+
 /*
  TODO:
 int qse_set_proc_name (const qse_char_t* name)