diff --git a/winsup/w32api/ChangeLog b/winsup/w32api/ChangeLog
index 2b84ef612..11fbf5dc5 100644
--- a/winsup/w32api/ChangeLog
+++ b/winsup/w32api/ChangeLog
@@ -1,3 +1,7 @@
+2010-09-22  Ryan Lortie  <desrt@desrt.ca>
+
+	* include/winbase.h (TzSpecificLocalTimeToSystemTime): Define.
+
 2010-12-27  Markus Koenig  <basilo@users.sourceforge.net>
 
 	* include/gdiplus/gdipluspixelformats.h (PixelFormatIndexed,
diff --git a/winsup/w32api/include/winbase.h b/winsup/w32api/include/winbase.h
index 700057e8f..c8a5b3122 100644
--- a/winsup/w32api/include/winbase.h
+++ b/winsup/w32api/include/winbase.h
@@ -2138,6 +2138,9 @@ WINBASEAPI DWORD WINAPI SuspendThread(HANDLE);
 WINBASEAPI void WINAPI SwitchToFiber(PVOID);
 WINBASEAPI BOOL WINAPI SwitchToThread(void);
 WINBASEAPI BOOL WINAPI SystemTimeToFileTime(const SYSTEMTIME*,LPFILETIME);
+#if (_WIN32_WINNT >= 0x501)
+WINBASEAPI BOOL WINAPI TzSpecificLocalTimeToSystemTime(LPTIME_ZONE_INFORMATION,LPSYSTEMTIME,LPSYSTEMTIME);
+#endif
 WINBASEAPI BOOL WINAPI SystemTimeToTzSpecificLocalTime(LPTIME_ZONE_INFORMATION,LPSYSTEMTIME,LPSYSTEMTIME);
 WINBASEAPI BOOL WINAPI TerminateProcess(HANDLE,UINT);
 WINBASEAPI BOOL WINAPI TerminateThread(HANDLE,DWORD);