diff --git a/qse/include/qse/cmn/time.h b/qse/include/qse/cmn/time.h
index ec286ea0..28a75fca 100644
--- a/qse/include/qse/cmn/time.h
+++ b/qse/include/qse/cmn/time.h
@@ -129,7 +129,7 @@ struct qse_btime_t
 	static QSE_INLINE void qse_cleartime(qse_ntime_t* x) {	qse_inittime (x, 0, 0); }
 	/*static QSE_INLINE int qse_cmptime(qse_ntime_t* x, qse_ntime_t* y)
 	{
-		/* TODO: fix the type and value range issue and replace the macro below.
+		// TODO: fix the type and value range issue and replace the macro below.
 		return (x->sec == y->sec)? (x->nsec - y->nsec): (x->sec - y->sec);
 	}*/
 #	define qse_cmptime(x,y) (((x)->sec == (y)->sec)? ((x)->nsec - (y)->nsec): ((x)->sec - (y)->sec))
diff --git a/qse/include/qse/si/App.hpp b/qse/include/qse/si/App.hpp
index 0789ffd3..4032c2bd 100644
--- a/qse/include/qse/si/App.hpp
+++ b/qse/include/qse/si/App.hpp
@@ -31,6 +31,7 @@
 #include <qse/Uncopyable.hpp>
 #include <qse/cmn/Mmged.hpp>
 #include <qse/cmn/Bitset.hpp>
+#include <qse/cmn/time.h>
 
 /////////////////////////////////
 QSE_BEGIN_NAMESPACE(QSE)
@@ -56,6 +57,9 @@ public:
 	int chroot (const qse_mchar_t* mpath) QSE_CPP_NOEXCEPT;
 	int chroot (const qse_wchar_t* wpath) QSE_CPP_NOEXCEPT;
 
+	void sleep (const qse_ntime_t* duration) QSE_CPP_NOEXCEPT;
+	void sleep (unsigned int seconds) QSE_CPP_NOEXCEPT;
+
 #if 0
 	int switchUser (qse_uid_t uid, qse_gid_t gid, bool permanently) QSE_CPP_NOEXCEPT;
 	int restoreUser () QSE_CPP_NOEXCEPT;
diff --git a/qse/lib/si/App.cpp b/qse/lib/si/App.cpp
index bc6bfd79..3c14a2ea 100644
--- a/qse/lib/si/App.cpp
+++ b/qse/lib/si/App.cpp
@@ -27,9 +27,11 @@
 #include <qse/si/App.hpp>
 #include <qse/si/Mutex.hpp>
 #include <qse/si/sinfo.h>
+#include <qse/si/os.h>
 #include "../cmn/syscall.h"
 #include <qse/cmn/mbwc.h>
 
+
 /////////////////////////////////
 QSE_BEGIN_NAMESPACE(QSE)
 /////////////////////////////////
@@ -190,6 +192,17 @@ int App::chroot (const qse_wchar_t* wpath) QSE_CPP_NOEXCEPT
 	return n;
 }
 
+void App::sleep (const qse_ntime_t* duration) QSE_CPP_NOEXCEPT
+{
+	qse_sleep (duration);
+}
+
+void App::sleep (unsigned int seconds) QSE_CPP_NOEXCEPT
+{
+	static qse_ntime_t duration = { seconds, 0 };
+	qse_sleep (&duration);
+}
+
 #if 0
 int App::switchPrivilege (int gid, int uid, bool permanently)
 {